Raju

Students can access the CBSE Sample Papers for Class 12 Biology with Solutions and marking scheme Term 2 Set 3 will help students in understanding the difficulty level of the exam.

CBSE Sample Papers for Class 12 Biology Standard Term 2 Set 3 with Solutions

Time Allowed: 2 Hours
Maximum Marks: 40

General Instructions:

• All questions are compulsory.
• The question paper has three sections and 13 questions. All questions are compulsory.
• Section-A has 6 questions of 2 marks each; Section-B has 6 questions of 3 marks each; and Section-C has a case-based question of 5 marks.
• There is no overall choice. However, internal choices have been provided in some questions. A student has to attempt only one of the alternatives in such questions.
• Wherever necessary, neat and properly labeled diagrams should be drawn.

SECTION – A
(Section A has 6 Questions of 2 marks each.)

Question 1.
(A) During a discussion on biodiversity, the
teacher showed the following picture of Amazon rainforest and labelled it as Lungs of the Planet. Why Amazon rainforest are termed as ‘Lungs of the Planet’?

(B) Name any two biodiversity hotspots of India. (2)
Answer:
(A) Among all the rainforests found on Earth, the largest one is Amazon rainforest. In Amazon rainforest, billions of tree and plant species are present. They take in tonnes of carbon dioxide and converts it to oxygen. This rainforests contributes about 18% to 20% of the world oxygen. Thus, they are considered as the lungs of the planet.

Related Theory
Rainforests refer to those forests where there is continuous rainfalL It constitute some of the globe’s most important ecosystems and environments. The globe’s rainforests cover nearly 2% of the earth’s total surface area and host more than 50% of the world’s animals and plants.

(B) The two biodiversity hotspots of India are:

1. Western Ghats and Sri Lanka
2. Indo-Burma
3. Himalaya (Any two)

Question 2.
(A) Reema was buying vegetables from the
supermarket and she noticed one of the labels as GM foods. What do you mean by GM foods?
(B) Many multinational companies use bioresources without authorization from the concerned country and its people.
What is this practice called? (2)
Answer:
(A) Genetically modified (GM) foods are defined as the foods that are derived from organisms whose genetic material (DNA) has been manipulated by incorporating a gene that will express a desirable trait.

Related Theory
The organisms in which DNA is manipulated are known as genetically modified organisms/transgenic/ genetically engineered.

(B) The practice of exploiting the bioresources by the multinational companies and organizations without authorization from the concerned country and its people is called as Biopiracy.

Question 3.
What is the role of microbes in producing the following types of cheese?
(A) Swiss cheese
(B) Roquefort cheese
OR
Why eradication of insect pests is not recommended by organic farmers? (2)
Answer:
(A) ‘Swiss cheese’: in this kind of cheese the
large holes are formed due to production of a large amount of CO₂ by a bacterium named Propionibacterium shermanii.

(B) ‘Roquefort cheese’: are ripened by growing a specific fungus known as Penicillium roqueforti on them, that gives them a particular flavour.
OR
Organic farmers believe that ‘biodiversity furthers health’. They do not recommend eradication of insect pests because in their absence the beneficial predatory and parasitic insects that depend on them as food or hosts would not be able to survive.

Related Theory
Organic farming requires the knowledge and understanding of various life forms present in the field such as predators, pests, their life cycles, patterns of feeding and the habitats that they prefer, so that they can be used in biocontrol measures. Ultimately, this will greatly reduce our dependence on toxic and harmful chemicals and pesticides.

Question 4.
The given diagram shows the release of histamine near an injury site in the body. Discuss the role of histamine in inflammatory response.

Explain the role of lymph nodes (secondary lymphoid organs) in our immune system. 2
Answer:
Histamine is released by basophils and mast cells as a part of local immune response in order to cause inflammation. Histamine is an organic nitrogenous compound. Release of histamine causes the capillaries to become more permeable to the WBCs and as a result they attack the foreign bodies in the affected areas. Therefore, histamine causes inflammation so that other chemicals are also released out and help in the repair work.
OR
Lymph nodes are small solid structures that are present at different points along the lymphatic system. The function of the lymph nodes is to trap the microorganisms or other antigens that enters the lymph and tissue fluid. As a result, the antigens that are trapped in the Lymph nodes, bring about the activation of lymphocytes present there and thus elicit the immune response.

Related Theory
Secondary lymphoid organs are the sites where interaction of lymphocytes with the antigen takes place, which then proliferate and develop to become effector cells.

Question 5.
(A) Ruminant animals like cattle harbour methanogens in their rumen (a part of their digestive tract). What is the function of these methanogens?
(B) How Lactobacillus bacteria improve the nutritional quality of curd? (2)
Answer:
(A) Methanogens (anaerobic microbes) help in the digestion of cellulose in the rumen of the cattle.

(B) Lactobacillus bacteria improve the nutritional quality of curd by increasing the amount of a nutrient, Vitamin B₁₂.

Question 6.
Tobacco smoking is very harmful for the person’s health as it leads to severe consequences like oxygen deficiency in blood. How does tobacco smoking lead to oxygen deficiency in human body? (2)
Answer:
There is an increase in the content of carbon monoxide (CO) in the blood of the person who smokes tobacco. CO has greater affinity to haemoglobin than oxygen and forms a stable bond with haemoglobin and does not allow oxygen to bind. This results in reduction of oxygen carrying capacity of haemoglobin. As a result, this reduces the content of haemoglobin bound oxygen and leads to oxygen deficiency in human body.

Related Theory
Due to tobacco smoking less oxygen reaches the mind, heart, muscle tissue and different organs. Therefore, lung function is reduced due to the narrowing of the lung airways and extra mucus in the lungs. Smoking also damages alveolar walls, which reduces respiratory surface (emphysema).

SECTION – B
(Section B has 6 Questions of 3 marks each.)

Question 7.
(A) The following picture shows the roots of a tobacco plant infected with nematode MeLoidogyne incognita, which decreases the yield and quality of tobacco plants. How the nematode infection in the roots of tobacco plants controlled with the process of RNA interference?

(B) A cow named “Rosie” was a transgenic cow. Why it is considered to be different from a normal cow?
OR
Enlist any three transgenic organisms and their application. 3
Answer:
(A) In the technique of RNA interference or gene silencing, nematode specific genes/ DNA is introduced in the host plant. This DNA then produces two types of RNA – sense and anti-sense RNA. As a result, these two strands of RNA, binds with each other to form a double-stranded RNA as they both are complementary to each other in sequence. Since dsRNA cannot translate, as a result, its expression is blocked and thus it leads to RNA interference. Therefore, the mRNA of nematode is silenced and the parasite cannot survive in the transgenic host.

Related Theory
The roots of tobacco plants are infected by a nematode Meloidogyne incognita.

(B) The transgenic cow “Rosie” do not produce only normal milk like other cows, but it produced human protein-enriched milk (2.4 g/L). Human alpha-lactalbumin was present in the milk and was nutritionally a more balanced product for human babies than natural cow-milk.

Related Theory
Rosie was the first transgenic cow created in 1997.

Caution
Students should remember that Rosie was the first transgenic cow, but the first transgenic animal was a mouse. Almost 95% of all transgenic animals are mice. These transgenic mice are developed for the purpose of studying human physiology and development.
OR
Following table shows the transgenic organisms and their application;

Question 8.
A hypothesis was proposed to explain the importance of biodiversity for survival of species. Who gave this hypothesis? Explain the hypothesis briefly. (3)
Answer:
Paul Ehrlich, a Stanford ecologist, gave ‘rivet popper hypothesis’ to explain the importance of biodiversity for survival of species.

• In his hypothesis, he considered the ecosystem as an airplane, in which all parts are joined together using thousands of rivets (species).
• If every passenger, travelling in it, starts popping a rivet to take home (causing a species to become extinct), it may not affect flight safety (proper functioning of the ecosystem) initially, but as more and more rivets are removed, the plane becomes dangerously weak over a period of time.
• Also, which rivet is removed may also be critical. For example, loss of rivets on the wings (key species that drive major ecosystem functions) is obviously a more serious threat to flight safety than loss of a few rivets on the seats or windows inside the plane.

Question 9.
Akshat became curious after seeing a very large vessel in a factory in which millions of microorganisms were cultured to produce a recombinant protein. The scientists told him that it was a bioreactor. Can you define bioreactor for him? Also, list the various components of a bioreactor. (3)
Answer:
To produce the cloned gene of interest on a large scale, the large volume vessels called as bioreactors, having a capacity of approximately 100-1000 liters are used, in which raw materials are biologically converted into specific products, individual enzymes, etc., using microbial plant, qnimal or human cells. The various components of a bioreactor are:

• Agitator system
• Oxygen delivery system
• Foam control system
• Temperature and pH control system
• Sampling port to withdraw periodically.

Related Theory
A bioreactor provides the optimal conditions for producing the desired product by providing optimum growth conditions like temperature, pH, substrate, salts, vitamins and oxygen.

Question 10.
An instructor showed a slide to students depicting Anabaena and a picture of mycorrhiza, both of which act as biofertilisers. How do Anabaena and mycorrhiza act as biofertilisers? (3)

Answer:
Fungi form symbiotic associations with plants which are known as mycorrhiza. In such associations, the fungal symbiont absorbs phosphorus from soil and transfers it to the plant. Many members of the genus Glomus form mycorrhiza.

Cyanobacteria are the autotrophic microbes that are found in aquatic and terrestrial environments. Many of them can fix atmospheric nitrogen, for example: Anabaena, Nostoc, Oscillatoria, etc., and serve as an important biofertilizer in paddy (rice) fields. Cyanobacteria also add organic matter to the soil and thereby increases its fertility.

Related Theory
Biofertilisers are organisms which enrich the nutrient quality of the soil by increasing the availability of nutrients to the crops.

Question 11.
(A) Give reasons for the following:

• Enzyme cellulose is needed to isolate genetic material from plant cells and not from animal cells.
• Exonuclease are not used for creating a recombinant DNA molecule.

(B) Who were responsible for the synthesis of first recombinant DNA molecule and in which year? (3)
Answer:
(A) (i) The plant cell wall is made up of cellulose, therefore, in order to digest cellulosic cell wall the enzyme cellulose is used, whereas the animal cells lack a cell wall and thus they do not need this enzyme.
(ii) Exonucleases are not used for creating rDNA molecule because they only remove the nucleotides from the ends of DNA molecule and not at any particular desired site/region within DNA.

(B) In 1972, Stanley Cohen and Herbert Boyer synthesized the first recombinant DNA molecule.

Question 12.
Classify the following diseases as infectious diseases and non-infectious disease. Also mention the basis of your classification. (3)
(a) Scurvy
(b) Cancer
(c) Syphilis
(d) AIDS
Answer:
Infectious diseases – Syphilis, AIDS
Non-lnfectious diseases – Scurvy, Cancer Basis of classification: Infectious diseases are those diseases that are easily transmitted from one person to another via pathogens. Non- infectious diseases are those which cannot be transmitted from one person to another and are not caused by pathogens. The cause of such diseases are nutritional deficiencies, malfunctioning of organs, etc.

Related Theory
Since infectious diseases are transmitted from one person to another via pathogens, such as, the cause of Syphilis is a bacterium called Treponema pallidum and AIDS spreads through Human Immunodeficiency Virus (HIV).

Caution
In case of non-infectious diseases, pathogens are do not play any role, such as Scurvy is caused by Vitamin C deficiency and cancer is caused by Oncogenic transformation of cells due to carcinogens such as X-rays, UV rays, etc.

SECTION – C
(Section C has a case-based question of 5 marks.)

Question 13.
The given picture depicts an animal named kangaroo rat that seldom drinks water. It has a thick coat to minimise evaporation and rarely comes out of its humid and cool burrow during day time. 90% of its water requirement is met by metabolic water which is produced by respiratory breakdown of fats whereas 10% is obtained from the food. It conserves water by producing almost solid urine and faeces.
Based on this answer the following questions:

(A) Kangaroo rats live in deserts, which are very hot and dry. How does the kangaroo rat get the water it needs?

(B) Due to the adaptations shown by Kangaroo rat, it is said to be a regulator. Justify the statement by defining it.

(C) Kangaroo rat is able to perform homeostasis. How would you define homeostasis?

(D) List any two adaptations of kangaroo rat that helps it to survive in a hot and dry climate.
OR
The teacher presented the following two pictures to her students in order to make them understand about the carrying capacity of a population.
Based on this answer the following questions:

(A) Which factors are responsible for decreasing the density of a population in a given habitat?
(B) Which growth curve is followed by human population?
(C) What does niche overlap indicates?
(D) Differentiate between immigration and emigration. (5)
Answer:
(A) Kangaroo rat get the water from the seeds it eats.
Explanation: Kangaroo rats get the water they need from food. They eat mostly seeds. 90% of its water requirement is met by metabolic water which is produced by respiratory breakdown of fats whereas 10% is obtained from the food.

(B) Kangaroo rat is a regulator because it performs homeostasis with the help of thermoregulation and osmoregulation by behavioural changes and physiological adjustments.

(C) Homeostasis is the process by which the organisms try to maintain the constancy of its internal environment despite varying external environmental conditions.

(D) The kangaroo rat is adapted to desert Life. The adaptations are as follows:
(i) They can survive without drinking water, by getting moisture from their fatty seed diet.
(ii) Produce concentrated urine and do not use water for regulation of body temperature.

OR
(A) The factors that are responsible for decreasing the density of a population in a given habitat are mortality and emigration.

(B) S-shaped growth curve is followed by human population.

(C) Niche overlap indicates that there is sharing of one or more resources between the two species.
(D)

Students can access the CBSE Sample Papers for Class 12 Geography with Solutions and marking scheme Term 2 Set 9 will help students in understanding the difficulty level of the exam.

CBSE Sample Papers for Class 12 Geography Term 2 Set 9 with Solutions

Time Allowed: 2 Hours
Maximum Marks: 35
Roll No. ___________

General Instructions:

• Question paper is divided into 5 sections A, B, C, D & E
• In section A, question number 1 to 3 are Very Short Answer type questions. Attempt any 3 questions.
• In section B, question number 4 is Source based question.
• In section C, question number 5 & 6 are Short Answer type questions.
• In section D, question number 7 to 9 are Long Answer type questions.
• In section E, question number 10 is a Map based question.

Section – A
Very Short Answer Questions

Question 1.
Describe the Trans-Siberian Railways mentioning all its important routes and stations. (2)
Or
Why are sea routes considered an important type of water transport?
Answer:
The Trans-Siberian Railways is major rail route of Russia which runs from St. Petersburg in the west to Vladivostok on the Pacific Coast in the east passing through Moscow, Ufa, Novosibirsk, Irkutsk, Chita and Khabarovsk. It is the most important route in Asia and the longest (9,332 km) double-tracked and electrified TransContinental Railway in the world. It runs across the Ural Mountains Ob and Yenisei rivers Chita is an important agrocentre and Irkutsk, a fur centre. Sea routes considered an important type of water transport because

• The oceans offer a smooth highway traversable in all directions with no maintenance costs.
• Compared to land and air, ocean transport is a cheaper means of haulage (carrying of load) of bulky material over long distances from one continent to another.

Question 2.
Identify the important minerals required for the production of nuclear energy and outline their distribution in India.
Answer:
Important minerals used for the generation of nuclear energy are uranium and thorium. Uranium deposits occur in the Dharwar rocks. Geographically, uranium ores are known to occur in several locations along the Singbhum Copper belt. Thorium is mainly obtained from monazite and ilmenite in the beach sands along the coast of Kerala and Tamil Nadu.

Question 3.
Discuss the highways of China and India.
Answer:
In China, highways criss-cross the country connecting all major cities such as Tsungtso (near Vietnam boundary), Shanghai (central China), Guangzhou (south) and Beijing (north). A new highway links Chengdu with Lhasa in Tibet. In India, there are many highways linking the major towns and cities. For example, National Highway No. 7 (NH 7), connecting Varanasi with Kanya Kumari, is the longest in the country.

Section – B
Source Based Question

Question 4.
Read the source given below and answer the following questions by choosing the correct options.
Oil and Gas Pipelines. Pipelines are the most convenient and efficient mode of transporting liquids and gases over long distances. Even solids can also be transported by pipelines after converting them into slurry.

Oil India Limited (OIL) under the administrative set up of the Ministry of Petroleum and Natural Gas is engaged in the exploration, production and transportation of crude oil and natural gas. It was incorporated in 1959 as a company. Asia’s first cross country pipeline covering a distance of 1,157 km was constructed by OIL from Naharkatiya oilfield in Assam to Barauni refinery in Bihar. It was further extended up to Kanpur in 1966.

Another extensive network of pipelines has been constructed in the western region of India of which Ankleshwar-Koyali, Mumbai High Koyali and Hazira-Vijaipur-Jagdishpur (HVJ) are most important. Recently, a 1256 km long pipeline connecting Salaya (Gujarat) with Mathura (UP) has been constructed. It supplies crude oil from Gujarat to Punjab (Jalandhar) via Mathura. OIL is in the process of constructing of 660 km long pipeline from Numaligarh to Siliguri.

i. Oil and gas are examples of which source of energy?
Answer:
Oil and gas are examples of non-renewable and exhaustible source of energy.

ii. Asia’s first cross country pipeline constructed by OIL connects which places?
Answer:
Asia’s first cross country pipeline was constructed by OIL connects Naharkatiya oilfield in Assam to Barauni refinery in Bihar and Kanpur.

iii. Oil India Limited was listed as a company in 1959. It is under which ministry?
Answer:
Oil India Limited was listed as a company in 1959. It is under the Ministry of Petroleum and Natural Gas.

Section – C
Short Answer Questions

Question 5.
Explain the ways in which landscape, history, art, culture and economy contribute to
tourism of a region.
Or
Explain how services occur at different levels and how are they regulated?
Answer:
Landscape, history, art, culture and economy contribute to tourism of a region in a following ways

Landscape Many people like to spend their holidays in an attractive environment, which often means mountains, lakes, spectacular sea coasts and landscapes not completely altered by man.

History and Art The history and art of an area have potential attractiveness. People visit ancient or picturesque towns and archaeological sites, and enjoy exploring castles, palaces and churches.

Culture and Economy These attract tourists with a penchant for experiencing ethnic and local customs. Besides, if a region provides for the needs of tourists at a cheap cost, it is likely to become very popular. Home-stay has emerged as a profitable business such as heritage homes in Goa, Madikere and Coorg in Karnataka.
Or
Services occur at many different levels. Some are geared to industry, some to people, and some to both industry and people, e.g. the transport systems. Low-order services, such as grocery shops and laundries, are more common and widespread than high-order services or more specialised ones like those of accountants, consultants and physicians.

Services are provided to individual consumers who can afford to pay for them. For example, the gardener, the launderers and the barber do primarily physical labour. Teacher, lawyers, physicians, musicians and others perform mental labour. Many services have now been regulated, for example

Making and maintaining highways and bridges, maintaining fire fighting departments and supplying or supervising education and customercare are among the important services most often supervised or performed by governments or companies. . State and union legislation have established corporations to supervise and control the marketing of such services as transport, telecommunication, energy and water supply.

Question 6.
Describe the railway network of Europe.
Answer:
Europe has one of the most dense rail networks in the world. There are about 4,40,000 km of railways, most of which is double or multiple-tracked. Belgium has the highest density of 1 km of railway for every 6.5 sq kms area. The industrial regions exhibit some of the highest densities in the world. The important rail heads are London, Paris, Brussels, Milan, Berlin and Warsaw.

Passenger transport is more important than freight in many of these countries. Underground railways are important in London and Paris. Channel Tunnel, operated by Euro Tunnel Group through England, connects London with Paris. Trans-continental railway lines have now lost their importance to quicker and more flexible transport systems of airways and roadways.

Section – D
This section consists of 3 questions of Long Answer Type
Long Answer Questions

Question 7.
Highlight the importance of tourism as a service ‘tertiary’ activity. What are the factors affecting tourism?
Or
What are the quaternary and quinary sectors of an economy?
Answer:
Tourism is travel undertaken for purposes of recreation rather than business. It is highly important because

It is the world’s single largest tertiary activity in total registered jobs (250 million) and total revenue (40 per cent of the total GDP)

Many local persons, are employed to provide services like accommodation, meals, transport, entertainment and special shops serving the tourists at the tourist location.

Tourism fosters the growth of infrastructure industries, retail trading, and craft industries (souvenirs). Factors affecting tourism are

Demand Since the last century, the demand for holidays has increased rapidly. Improvements in the standard of living and increased leisure time, permit many more people to go on holidays for leisure.

Transport The opening-up of tourist areas has been aided by improvement in transport facilities. Travel is easier by car, with better road systems. More significant in recent years has been the expansion in air transport. For example, air travel allows one to travel anywhere in the world in a few hours of flying time from their homes. The advent of package holidays has reduced the costs.
Or
Quaternary Sector Quaternary sector involve the collection, production and dissemination of information or even the production of information. Quaternary activities centre around research, development and may be seen as an advanced form of services involving specialised knowledge and technical skills.

Quaternary activities can consist of Information Technology (IT), media, Research and Development (R&D), information-based services such as information-generation and information-sharing and knowledge-based services such as consultation, education, financial planning and designing. The Quaternary Sector along with the Tertiary

Sector has replaced most of the primary and secondary employment as the basis for economic growth. Quinary Sector Quinary sector include the highest level of decision makers or policy makers. These are subtly different from the knowledge based industries that the quinary sector in general deals with. Quinary activities are services that focus on the creation, re-arrangement and interpretation of new and existing ideas; data interpretation and the use and evaluation of new technologies.

Question 8.
Discuss water pollution along with sources of pollution and its effects.
Answer:
Water pollution refers to a state where the natural taste, colour and odour of the water is contaminated.

Sources of Water Pollution

Water pollution can be caused by both natural and anthropogenic (human) sources. Natural sources include contamination from erosion, landslides, decay and decomposition of plants and animals, etc. Anthropogenic sources include contamination through industrial, agricultural and cultural activities.

Industries produce several undesirable products including industrial wastes, polluted waste water, poisonous gases, chemical residuals, numerous heavy metals, dust, smoke, etc. Major water polluting industries are leather, pulp and paper, textiles and chemicals.

Various types of chemicals used in modern agriculture such as inorganic fertilisers, pesticides and herbicides are also pollution generating components.

Cultural activities such as pilgrimage, religious fairs, tourism, etc. also cause water pollution. In India, almost all surface water sources are contaminated and unfit for human consumption.

Effects of Water Pollution

Water pollution is a source of various water-borne diseases.

Heavy metal contamination in polluted water such as mercury, arsenic and cadmium contamination can cause severe acute and chronic effects on human including Gastrointestinal and kidney dysfunction, nervous system disorders, skin lesions, and cancer, etc.

Question 9.
Rapid growing population is resulting in an equivalent increase in resource consumption and waste generation. Limited technology and infrastructure often results in accumulation of waste. In this context, discuss urban waste disposal and issues related to it.
Answer:
The processing of waste generated in urban areas is known as urban waste disposal. Human population and related consumption resources is rapidly increasing. This led to generation of large amount of waste in urban house holds and industries. Urban waste disposal is a serious problem in India. In metropolitan cities like Mumbai, Kolkata, Chennai, Bengaluru, etc., about 90 per cent of the solid waste is collected and disposed. The issues related to urban waste disposal are

The huge turnout of ashes and debris from industries, thermal power houses and building constructions or demolitions have contributed to land, air and water pollution

Solid wastes cause health hazard through creation of obnoxious smell, and harbouring of flies and rodents, which act as carriers of diseases like typhoid, diphtheria, diarrhea, malaria and cholera, etc.

Concentration of industrial units in and around urban centres gives rise to disposal of industrial wastes. The dumping of industrial waste into rivers leads to water pollution. Serious health problems downstream.

Section – E
Map Based Question

Question 10.
On the political map of the world, identify the following features (Attempt any 5). (1 × 5 = 5)
A. The Terminal Station of Trans-Continental Railway
B. A major airport
C. An international airport
D. A major seaport
E. A major seaport
F. A canal

Answer:

Students can access the CBSE Sample Papers for Class 12 Geography with Solutions and marking scheme Term 2 Set 8 will help students in understanding the difficulty level of the exam.

CBSE Sample Papers for Class 12 Geography Term 2 Set 8 with Solutions

Time Allowed: 2 Hours
Maximum Marks: 35
Roll No. ___________

General Instructions:

• Question paper is divided into 5 sections A, B, C, D & E
• In section A, question number 1 to 3 are Very Short Answer type questions. Attempt any 3 questions.
• In section B, question number 4 is Source based question.
• In section C, question number 5 & 6 are Short Answer type questions.
• In section D, question number 7 to 9 are Long Answer type questions.
• In section E, question number 10 is a Map based question.

Section – A
Very Short Answer Questions

Question 1.
Describe the highways of any one developed region of the world. (2)
Answer:
In developed countries, every city and port town is linked through highways. For example, in North America, highway density is high, about 0.65 km per sq km. Every place is within 20 km distance from a highway. Cities located on the Pacific coast (west) are well-connected with those of the Atlantic Coast (East). Likewise, the cities of Canada in the north are linked with those of Mexico in the South.

Question 2.
Define transport (2)
Or
Explain the dependence of transportation on distance and volume of passenger or cargo by giving examples.
Answer:
Transport is a service or facility for the carriage of persons and goods from one place to the other using humans, animals and different kinds of vehicles. Such movements take place over land, water and air. Roads and railways form part of land transport; while shipping and waterways and airways are the other two modes. Transportation depends on distance and volume of passenger or cargo. For example,

• Road transport is cheaper and faster over short distances and for door-todoor services.
• Railways are most suited for large volumes of bulky materials over long distances within a country.

Question 3.
State the objective and activities of NITI Aayog. (2)
Answer:
NITI Aayog has been set up with the objective of involving the states in economic policy making for India for providing strategic and technical advice to the Central and State governments. Its entire activities can be categorised as

• Policy and programme framework.
• Cooperative federalism
• Monitoring and evaluation
• Think tank and knowledge hub

Section – B
Source Based Question

Question 4.
Read the source given below and answer the following questions by choosing the correct options.
The pressure on agricultural land increases not only due to the limited availability but also by deterioration of quality of agricultural land. Soil erosion, waterlogging, salinisation and alkalinisation of land lead to land degradation. What happens if land is consistently used without managing its fertility? Land is degraded and productivity declines.

Land degradation is generally understood either as a temporary or a permanent decline in productive capacity of the land. Though all degraded land may not be wasteland, but unchecked process of degradation may lead to the conversion to wasteland. There are two processes that induce land degradation. These are natural and created by human beings.

National Remote Sensing Centre (NRSC) has classified wastelands by using remote sensing techniques and it is possible to categorise these wastelands according to the processes that have created them. There are a few types of wastelands such as gullied /ravinous land, desertic or coastal sands, barren rocky areas, steep sloping land, and glacial areas, which are primarily caused by natural agents.

There are other types of degraded lands such as waterlogged and marshy areas, land affected by salinity and alkalinity and land with or without scrub, which have largely been caused by natural as well as human factors. There are some other types of wastelands such as degraded shifting cultivation area, degraded land under plantation crops, degraded forests, degraded pastures, and mining and industrial wastelands are caused by human action.

i. What is the result of unregulated use of agricultural land? (1)
Answer:
Unregulated use of agricultural can result in increase in soil moisture and fertility.

ii. Land degradation can be temporary or permanent. What is the possible reason behind a permanent land degradation? (1)
Answer:
The possible reason behind a permanent land degradation could be ignorance of sign of degradation and no efforts to restore the land.

iii. Lands under shifting cultivation or selective plantation may degrade due to which factor? (1)
Answer:
Lands under shifting cultivation or selective plantation may degrade due to loss of soil fertility and moisture.

Section – C
Short Answer Questions

Question 5.
Explain how access to transportation and communication facilities affect the location of industries especially in the context of footloose industries. (3)
Or
Identify the reason behind the resulting of a ‘New-Ruhr’ landscape. Explain this ‘New-Ruhr’ landscape.
Answer:
Access to transportation and communication facilities greatly affect the location of industries. Modem industry is inseparably tied to transportation systems. Improvements in transportation led to integrated economic development and regional specialisation of manufacturing. The cost of transport and location of industries depends on speedy and efficient transport facilities to carry raw materials to the factory and to move finished goods to the market.

In this context, footloose industries can be located in a wide variety of places. The important factor in their location is accessibility by road network. They are not dependent on any specific raw material, weight losing or otherwise. They largely depend on component parts which can be obtained anywhere. They produce in small quantity and also employ a small labour force. These are generally not polluting industries.
Or
‘New-Ruhr’ landscape refers to the change in industrial and other economic activities in the Ruhr coal field region in Germany. The reason behind it is changing demands and structure in coal and steel industries. The Ruhr coal field in Germany has been one of the major industrial regions of Europe. Coal and iron and steel formed the basis of the economy, but as the demand for coal declined, the industry started shrinking.

Once the iron ore exhausted, the industry confirmed on imported ore. The Ruhr region is responsible for 80 per cent of Germany’s total steel production. However, changes in the industrial structure have led to the decay of some areas, and problems of industrial waste and pollution. The future prosperity of the Ruhr is based less on the products of coal and steel and more on the new industries like the huge Opel car assembly plant, new chemical plants, universities. Outof-town shopping centres have appeared resulting in a ‘New Ruhr’ landscape.

Question 6.
Differentiate between the distribution of mineral resources in the North Eastern Plateau region and South Western Plateau region of India. (3)
Answer:
Differences between the distribution of mineral resources in North Eastern Plateau region and South Western Plateau region are North Eastern Plateau Region This belt covers Chota Nagpur (Jharkhand), Odisha Plateau, West Bengal and parts of Chhattisgarh Major iron and steel industries are located in this region It has variety of minerals viz. iron ore coal, manganese, bauxite, mica.

The South-Western Plateau Region This belt extends over Karnataka, Goa and contiguous Tamil Nadu uplands and Kerala. This belt is rich in ferrous metals and bauxite. It also contains high grade iron ore, manganese and limestone. This belt packs in coal deposits except Neyveli lignite. This belt does not have as diversified mineral deposits as the North-Eastern belt. Kerala has deposits of monazite and thorium, bauxite clay. Goa has iron ore deposits.

Section – D
Long Answer Questions

Question 7.
Iron and steel industry are basic industry which are important for development of an economy. State its global distribution with details on major iron and steel producing countries.(5)
Or
Technology has revolutionised the global economies with faster and efficient production in all types of industries. Discuss the concept of ‘High technology industries’.
Answer:
The iron and steel industry is one of the most complex and capital-intensive industries and is largely concentrated in the advanced countries of North America, Europe and Asia. In 1970’s, Japan, USA and western Europe were accounting for 2/3rd global production of iron and steel. However, the developing nations such as China, India, Brazil and South Korea gradually became important steel producers. The global distribution of iron and steel industry is

In USA, most of the production comes from the north Appalachian region (Pittsburgh), Great Lake region (Chicago-Gary, Erie, Cleveland, Lorain, Buffalo and Duluth) and the Atlantic Coast (Sparrows Point and Morisville). The industry has also moved towards the southern state of Alabama. In Europe, U.K, Germany, France, Belgium, Luxembourgh, the Netherlands and Russia are the leading producers.

The important steel centres are Scun Thorpe, Port Talbot, Birmingham and Sheffield in the U.K.; Duisburg, Dortmund, Dusseldorf and Essen in Germany, Le Creusot and St. Ettienne in France, and Moscow, St. Petersburgh, Lipetsk, Tula, in Russia and Krivoi Rog, and Donetsk in Ukraine.

In Asia, the important centres include Nagasaki and Tokyo-Yokohama in Japan; Shanghai, Tienstin and Wuhan in China; and Jamshedpur, Kulti-Burnpur, Durgapur, Rourkela, Bhilai, Bokaro, Salem, Visakhapatnam and Bhadravati in India.
Or
High-tech industries refer to those industries where the major work force has technology based occupations, such as engineers and scientists. High technology, or simply high-tech, is the latest generation of manufacturing activities. Some of the key features of high-tech industries are

In these industries, application of intensive Research and Development (R and D) efforts leads to the manufacturing of products of an advanced scientific and engineering character. Professional (white collar) workers make up a large share of the total workforce. These highly skilled specialists greatly outnumber the actual production (blue collar) workers.

Robotics on the assembly line, Computer – aided Design (CAD) and manufacturing, electronic controls of smelting and refining processes, and the constant development of new chemical and pharmaceutical products are notable examples of a high-tech industry.

Neatly spaced, low, modern, dispersed, office-plant-lab buildings rather than massive assembly structures, factories and storage areas mark the high-tech industrial landscape. Planned business parks for high-tech start-ups have become part of regional and local development schemes. High-tech industries which are regionally concentrated, self-sustained and highly specialised are called technopolies. The Silicon Valley near San Francisco and Silicon Forest near Seattle are examples of technopolies.

Question 8.
Movement of people and goods is critical for economy. What is the role of land transport in Indian economy? (5)
Answer:
Land transport via pathways and unmetalled roads have been used for transportation in India since ancient times. Land transport is usually defined in two broad categories i.e. road transport and rail transport. The importance of land transport in Indian economy is

Road Transport India has one of the second largest road networks in the world. About 85 per cent of passenger and 70 per cent of freight traffic are carried by roads every year. Road transport is relatively suitable for connectivity and shorter distance travel. For the purpose of construction and maintenance, roads are classified as National Highways (NH), State Highways (SH), Major District Roads and Rural Roads.

Rail Transport Indian Railways network is one of the longest in the world and largest in Asia. It facilitates the movement of both freight and passengers by approx 11000 trains daily and contributes to the growth of the economy. Railways transport over 5 billion passengers and 350 million tones cargo annually. Indian Railways is the largest government undertaking in the country. Due to its very large size and consequent pressure on the centralised railway management system, the railway system in India has been divided into 16 zones.

Question 9.
Discuss the importance and distribution of waterways as form of water transport in India. (5)
Answer:
Waterways is an important mode of water transport for both passenger and cargo traffic in India in
the following ways

• It is the cheapest means of transport and is most suitable for carrying heavy and bulky material,
• It is a fuel-efficient and eco-friendly mode of transport. Water offers less resistance during movement in comparison to the land transport, and hence is fuel and cost effective.

Generally, there is no need to lay down new routes for water transport due to pre-existing river channels and water bodies, which further saves resources. The types of water transport with their distribution are

(i) Inland Waterways India has 14,500 km of navigable waterways, contributing about 1% to the country’s transportation. It comprises rivers, canals, backwaters, creeks, etc. There are a total of five national water ways in India, i.e.

• NW1 Allahabad-Haldia stretch, 1620 km.
• NW2 Sadiya-Dhubri stretch, 891 km
• NW3 Kottapuram-Kollam stretch, 205 km.
• NW4 Specified stretches of Godavari and Krishna rivers along with Kakinada Puducherry stretch of canals, 1078 km.
• NWS Specified stretches of river Brahmani along with Matai river, delta channels of Mahanadi and Brahmani rivers and East Coast canals, 588 km.

(ii) Oceanic Routes India has a vast coastline of approximate 7,517 km, including islands. Twelve major and 185 minor ports provide infrastructural support to these route Few examples of major ports are Kolkata, Mumbai, Chennai, Cochin, Paradip and Nhavasheva (LN Port). Majority of Indian ports are located along the Peninsular coast line of India. For example, in States of Tamil Nadu, Kerala, Kamataka, Odisha, etc.

Section – E
Map Based Question

Question 10.
On the political map of the world, identify the following features (Attempt any 5). (1 × 5 = 5)
A. An airport in Africa
B. A major sea port
C. A major airport
D. A seaport in south America
E. A major seaport in Australia
F. A major seaport in China
Answer:

Students can access the CBSE Sample Papers for Class 12 Economics with Solutions and marking scheme Term 2 Set 6 will help students in understanding the difficulty level of the exam.

CBSE Sample Papers for Class 12 Economics Term 2 Set 6 with Solutions

Time allowed: 2 Hours
Maximum Marks: 40

General Instructions:

• This is a Subjective Question Paper containing 13 questions.
• This paper contains 5 questions of 2 marks each, 5 questions of 3 marks each and 3 questions of 5 marks each.
• 2 marks questions are Short Answer Type Questions and are to be answered in 30-50 words.
• 3 marks questions are Short Answer Type Questions and are to be answered in 50-80 words.
• 5 marks questions are Long Answer Type Questions and are to be answered in 80-120 words.
• This question paper contains Case/Source Based Questions.

Question 1.
Distinguish between autonomous investment and induced investment.
OR
Distinguish between ex-ante investment and ex-post investment. (2)
Answer:
Autonomous investment refers to the investment which is independent of the level of income in the economy, whereas, induced investment changes as the rate of interest or level of income changes in the economy.

OR
Ex-ante investment is the desired or planned investment corresponding to different income levels in the economy whereas, ex-post investment is the actual investment in the economy during the period of one year.

Question 2.
From the following data, calculate:
(A) Consumption Expenditure and
(B) Investment Expenditure for the economy.

OR

If in an economy:
Change in initial Investments (Δl) = ₹500 crore
Marginal Propensity to Save (MPS) = 0.2

Find the values of the following:
(A) Investment multiplier (k)
(B) Change in final income (ΔY) (2)
Answer:
(A) We know that:
Consumption expenditure = C + bY
= 500 + 0.6 (5,000)
= ₹ 3,500 crore

(B) Also, at equilibrium level,
Y = C + 1
5,000 = 3,500 + l
l = 1,500 crore
OR
(A) K = 1/MPS
K = 1/0.2 = 5
(B) ΔY = K(ΔI)
ΔY = 5 x 500
= ₹ 2,500 crore

Question 3.
Are the following workers a beggar, a thief, a smuggler, a gambler? Why? (2)
Answer:
All those who are engaged in economic activities, in whatever capacity — high or low, are workers. Thus, they are not workers, as they are not engaged in any economic activity.

Question 4.
“India has emerged as a hotspot for medical tourism”. Defend the statement with valid arguments. (2)
Answer:
The given statement is defended as in the recent past India has witnessed many foreign nationals visiting for surgeries, organ transplant, dental and even cosmetic care. The prime reason for this phenomenon can be quoted as:

1. Health services in India offer latest medical technologies with qualified professionals.
2. All these medical services are less costly in India as compared to similar health care services in other countries.

Question 5.
Why is self-employed workforce higher in rural areas?
OR
Compare and analyze the distribution of working persons in different industries during the year 2017-18 on the basis of ‘gender or sex’. (2)
Answer:
Most of the rural people are mainly engaged in agriculture and do farming on their own plots thus, self-employed workforce higher in rural areas.
OR
Though both men and women workers are concentrated in the primary sector, women workers’ concentration is very high there. About 57 percent of the female workforce is employed in the primary sector whereas less than half of males work in that sector. Men get opportunities in both secondary and service sectors.

Question 6.
Which of the following items will be included/not included while estimating Gross Domestic Product? Give valid reasons in support of your answer.
(A) Wages received by an Indian working in the British Embassy in India
(B) Financial aids received from abroad after “Fani cyclone”
(C) Purchase of second-hand machinery from abroad. (3)
OR
If GDP_FC = ₹ 24,760, operating surplus = ₹ 13,450, mixed-income = ₹ 4,260 and consumption of fixed capital = ₹ 530, then what will be the value of compensation of employees? (3)
Answer:
(A) Wages received by an Indian working in British embassy in India is not a part of economic territory of India, as British Embassy is a part of Economic territory of Britain.

(B) Financial aid is a transfer income as no factor service is provided in return. Hence, it is not included while estimating the value of GDP.

(C) Purchase of second hand machinery from abroad is not included as the value of imports are deducted while estimation GDP of a country.
OR
GDP_FC = Operating Surplus + Mixed Income + Consumption of Fixed Capital + Compensation of Employees 24,760 = 13,450 + 4,260 + 530 + Compensation of Employees Compensation of Employees = 24,750 – 13,450 – 4,260 – 530 = ₹6,520

Question 7.
Give reasons for the slow growth and re-emergence of poverty in Pakistan. (3)
Read the following case carefully and answer question number 8 and 9 given below:

Some economists have projected that India will become the third biggest economy in the world a few decades from now. For that to happen, India will have to boost its infrastructure investment. In any country, as the income rises, the composition of infrastructure requirements changes significantly.

For low-income countries, basic infrastructure services like irrigation, transport and power are more important. As economies mature and most of their basic consumption demands are met, the share of agriculture in the economy shrinks and more service-related infrastructure is required. This is why the share of power and telecommunication infrastructure is greater in high-income countries.

Thus, development of infrastructure and economic development go hand in hand. Agriculture depends, to a considerable extent, on the adequate expansion and development of irrigation facilities. Industrial progress depends on the development of power and electricity generation, transport and communications. Obviously, if proper attention is not paid to the development of infrastructure, it is likely to act as a severe constraint on economic development.
Answer:
The reasons for the slowdown of growth and re-emergence of poverty in Pakistan’s economy are agricultural growth and food supply situation were based not on an institutionalized process of technical change but on good harvest. When there was a good harvest, the economy was in good condition, when it was not, the economic indicators showed stagnation or negative trends.

Question 8.
“Some economists have projected that India will become the third biggest economy in the world a few decades from now. For that to happen, India will have to boost its infrastructure investment.” Explain the importance of infrastructure in the light of this statement. (3)
Answer:
Infrastructure is critical to rapid economic growth and poverty eradication in the country. Adequate infrastructure in the form of a road and rail transport system, ports, power, airports and their efficiency are also needed to integrate the Indian economy and other world economies. The expansion in infrastructure facilities such as irrigation, rural electrification, roads and road transport will promote agricultural growth and setting up of agro-processing industries.

Question 9.
“The share of power and telecommunication infrastructure is greater in high-income countries.” Why? (3)
Answer:
In any country, as the income rises, the composition of infrastructure requirements changes significantly. For low-income countries, basic infrastructure services Like irrigation, transport and power are more important. As economies mature and most of their basic consumption demands are met, the share of agriculture in the economy shrinks and more service-related infrastructure is required. This is why the share of power and telecommunication infrastructure is greater in high-income countries.

Question 10.
Compare and analyse the given data of India and China with valid reasons:

Answer:
(A) The given data shows that China could arrest its annual population growth rate with the implementation of some stringent measures in late 1970’s like the introduction of one child norm. This step has been instrumental in controlling the growth of population in China. India stands virtually more than double to China at its annual population growth rate of 1.2% as compared to China’s annual population growth rate of 0.5% pa.

(B) The social dynamics of both the countries are similar to each other; sex ratio is low and biased in both the countries due to preference for male child. Whereas, India stands at 929 females per 1000 males, China is not far ahead at 941 females per 1000 males.

Question 11.
(A) “Gross Domestic Product (GDP) does not give us a clear indication of economic welfare of a country.” Defend or refute the given statement with valid reason.

(B) If in a locality, a new park is developed by the municipal corporation, it will have externalities, both positive and negative. State one example for each of both types of externalities with reason. (5)
Answer:
(A) Yes, given statement is defended. As GDP may not take into account

• Non-monetary exchanges like services of housewife
• Externalities i.e. benefits and harms which are caused due to economic activities
• Distribution of income.

(B) The park in neighborhood can be a source of positive externality as it helps in reducing pollution and thereby improving health and efficiency.

The park in a neighborhood can be a source of negative externality if it is used by anti-social elements. This can increase crime and lead to insecurity.

Question 12.
(A) Calculate national income from the following data: (₹ in crores)
(i) Private final consumption expenditure 900
(ii) Profit 100
(iii) Government final consumption expenditure 400
(iv) Net indirect taxes 100 M Gross domestic capital formation 250
(Vi) Change in stock 50
(vii) Net factor income from abroad (-)40
(viii) Consumption of fixed capital 20
(ix) Net imports 30

(B) Describe the expenditure method of calculating Gross Domestic Product at Market Price. (5)
OR
(A) Describe incomes from property and entrepreneurship.
(B) Calculate Gross Value Added at Market price (GVA_MP) from the following data: (5)

Answer:
(A) National Income = Private final consumption expenditure + Government final consumption expenditure + Gross domestic capital formation – Consumption of fixed capital – Net imports – Net indirect taxes + Net factor income from abroad = 900 + 400 + 250 – 20 – 30 – 100 + (-)40 = ₹1,360 crore

(B) To calculate GDPMP by the expenditure method, we add up final expenditures on the goods and services produced by all the economic sectors of an economy. Expenditures incurred on consumption and investment are final expenditures.

These are classified into:
(i) Private final consumption expenditure.
(ii) Government final consumption expenditure.
(iii) Gross domestic capital formation.
(iv) Net exports = Exports less Imports

The sum total of these expenditures is GDP_MP.
OR
(A) Incomes from property and entrepreneurship are incomes earned by property owners. It includes, rent and royalty, profit, interest. It can also be termed as Operating Surplus.

(B) GVAMP = [(ii)+(iii)+(iv)]-(v)
= [200 + (-)10 + 10] – 120
= 200 – 120
= ₹80 lakhs

Question 13.
Explain the determination of equilibrium level of national income using ‘saving and investment’ approach. Use diagram. Also explain the effects if saving is greater than investment. (5)
Answer:
The equilibrium is where S = l
i.e. at E, where the savings curve ‘S’ and investment curve ‘l’ intersect.

If S > I, it means AD < AS. This leads to unplanned inventories.

Producers reduce output till S = I again.

Students can access the CBSE Sample Papers for Class 12 Biology with Solutions and marking scheme Term 2 Set 2 will help students in understanding the difficulty level of the exam.

CBSE Sample Papers for Class 12 Biology Standard Term 2 Set 2 with Solutions

Time Allowed: 2 Hours
Maximum Marks: 40

General Instructions:

• All questions are compulsory.
• The question paper has three sections and 13 questions. All questions are compulsory.
• Section-A has 6 questions of 2 marks each; Section-B has 6 questions of 3 marks each; and Section-C has a case-based question of 5 marks.
• There is no overall choice. However, internal choices have been provided in some questions. A student has to attempt only one of the alternatives in such questions.
• Wherever necessary, neat and properly labeled diagrams should be drawn.

SECTION – A
(Section A has 6 Questions of 2 marks each.)

Question 1.
Give reasons for the following:
(A) An inoculum of curd is added to milk for curdling it.
(B) Dough has a puffed-up appearance.
OR
Why it is considered beneficial to construct a biogas plant in rural areas? (2)
Answer:
(A) The inoculum contains millions of Lactic acid bacteria (LAB) or Lactobacilli which have the ability to convert the lactose sugar present in the milk into lactic acid. This lactic acid results in coagulation and digestion of milk protein casein. Therefore, the milk changes into curd.

(B) The dough has a puffed-up appearance due to the production of CO₂ gas which is produced through the process of fermentation by bacteria.
OR
Cattle dung serves as the raw material for the biogas plant and it is available in plenty amount in rural areas. In agriculture, the spent slurry from the biogas plant is used as a manure. Also, the biogas is used for lighting and cooking in rural areas as distribution is only in short distances. Therefore, it is beneficial to construct a biogas plant in rural areas.

Question 2.
The diagram given below shows the formation of a tumour in between the normal cells. The cancer cells divide uncontrollably. Name the process in which the cells from these tumours migrate through blood or lymph to other parts of the body, and wherever they get lodged in the body, they result in the development of a new tumour. Which kind of tumour is shown this process? (2)

Answer:
The process in which the cells of the tumours migrate through blood or lymph to other parts of the body, and wherever they get lodged in the body, they result in the development of a new tumour is called as Metastasis.
The process of Metastasis is shown by malignant tumours.

Question 3.
In the diagram given below, a bacterial cell is shown. Write the name of the part labeled as part ‘A’ and ‘B’. Also mention the use of part ‘A’ in rDNA technology. (2)

Answer:
The name of the part labeled as part ‘A’ and ‘B’ is:
A – PLasmid,
B – Nucleoid
In rDNA technology, plasmid is used as a cloning vector to transfer the gene of interest into the host cell.

Question 4.
(A) Ramesh explained Riya that ecology is defined as the branch of science that deals with the study of the interactions among organisms. Elaborate the definition to make her understand better.
(B) Due to global warming, Life of many organisms has changed and became difficult. Which among eurythermal or stenothermal organisms can cope up better during global warming? (2)
Answer:
(A) Ecology is the field that deals with the balance between development and maintenance of natural environment and biotic communities, use and conservation of resources, finding solutions of local, regional and global environmental problems.

(B) The organisms that can cope up better during global warming are Eurythermal organisms. These organisms have greater adaptability.

Related Theory
Eurythermal are the organisms that can tolerate and thrive in a wide range of temperatures. Examples: most mammals and birds. Stenothermal are the organisms that can tolerate a narrow range of temperatures. Example: amphibians.

Question 5.
(A) Roma was wondering about the diverse organisms present around her. She was excited by the fact that so many different types of plants and animals and even microorganisms are present around us. What is the term used for this? Define it.
(B) Within a species, how different sub¬species, variety, breeds and forms are created? illustrate with an example. (2)
Answer:
(A) The variety of life on earth at all its levels, from genes to ecosystems is referred to as biodiversity. Biodiversity can be simply defined as the number and variety of organisms found within a specified geographic region. It refers to the varieties of plants, animals and microorganisms, the genes they contain and the ecosystems they form.

(B) Different sub-species, variety, breeds, forms are formed due to genetic diversity within the species.
Example: The medicinal plant Rauwolfia vomitoria growing in different Himalayan ranges shows genetic variation in terms of the potency and concentration of the active chemical called reserpine that the plant produces.

Related Theory
Genetic diversity is defined as the measure of variety of genetic information contained within the species. Another example is: India has more than 50,000 genetically different strains of rice, and 1,000 varieties of mango.

Question 6.
(A) After the Covid-19 pandemic, government is stressing on vaccination campaign. What is it that prevents a person to suffer from a disease he/she is vaccinated against? Give one reason.
(B) It is advised to avoid crowded and closed places like cinema halls, etc, during What do you mean by withdrawal syndrome changing weather. Why? jn case of drug and alcohol abuse? (2)
Answer:
(A) The vaccine contains the dead pathogen that provokes the active immunity of an individual leading to the formation of antibodies that protect him/her from the disease.

Related Theory
Active Immunity: When an individual (host) is exposed to antigens in the form of living or dead microbes or other proteins. It results in the production of antibodies. This kind of immunity is slow and thus takes time to give its full effective response, but its effect is long lasting. It has no side effects.

An active immunity is induced in our body by deliberately injecting the microbes/antigens either through immunization/vaccination (termed as artificial immunity) or through natural infection by infectious organisms (termed as natural immunity).

(B) During changing weather, the germs or pathogens are more active and prevalent in the atmosphere as the conditions are suitable for their growth and these pathogens are more in crowded and closed places. Therefore, the chances of infection are high in such places.

Related Theory
Infectious agents are more active during changing weather as moist conditions favors the growth of pathogens. Also, at that time the body of the individual is adapting the changing environmental conditions of temperature, humidity, etc., so the person is more vulnerable to diseases and thus can easily get infected by these pathogens.
OR
Withdrawal syndrome is also known as discontinuation syndrome. This occurs in individuals who have developed physiological dependence on drugs or alcohol and who discontinue or reduce their use of it.

Related Theory
The person becomes addicted and dependent on drugs or alcohol in the absence of any guidance or counselling. The tendency of the body to manifest a characteristic and unpleasant withdrawal syndrome if regular dose of drugs/alcohol is abruptly discontinued is called as Dependence. The withdrawal symptoms include anxiety, shakiness, nausea and sweating that are relieved when use is resumed again. The withdrawal symptoms can be severe and even life threatening and the person may require medical supervision. The patient can break all social norms in order to get sufficient funds to satiate his/her needs due to dependence on drugs or alcohol. This can lead to many social adjustment problems.

SECTION – B
(Section B has 6 Question of 3 marks each.)

Question 7.
(A) Suhani and her friends went for
educating their colony regarding the spread of diseases via mosquitoes. They emptied all the overhead tanks, which were not in use for last few months. What was the purpose of this act? Name the pathogen which is responsible for causing malaria (mosquito borne disease).

(B) The thymus gland of a person is removed. Will the immune system of that person be affected? If yes, how? (3)
Answer:
(A) The purpose behind emptying the overhead tanks was to prevent mosquito borne diseases as the water in the tanks was stagnant and can become a breeding ground for the mosquitoes. The pathogen which is responsible for causing malaria is Plasmodium (a protozoan).

(B) Thymus gLand is a primary lymphoid organ where immature lymphocytes differentiate into antigen-sensitive lymphocytes. Therefore, removal of thymus gland makes the immune system weak and as a result the person’s body becomes more prone to infectious diseases.

Question 8.
The following picture shows the three basic steps of genetic engineering. Write down these steps briefly.

OR
One of the crucial steps of genetic engineering is the identification of recombinant DNA containing the desired gene. This is done by a process called insertional inactivation. Explain this process with the help of an example. (3)
Answer:
The three basic steps of genetic engineering or making a Genetically Modified Organism(GMO) are:
(i) Identification of DNA with desirable genes.
(ii) Introduction of the identified DNA into the suitable host to form recombinant DNA (rDNA).
(iii) Maintenance of introduced DNA in the host and transfer of the DNA to its progeny.
OR
Insertional inactivation refers to the insertion of a certain gene in the host DNA at a particular site. Due to this insertion, the function of the gene at whose site insertion has taken place gets inactivated. This process is used to identify recombinant DNA containing organisms from those who are non-recombinants.

Example: A recombinant DNA is inserted within the coding sequence of an enzyme, (3-galactosidase, that results into inactivation of the gene for synthesis of this enzyme. This is known as insertional inactivation. If the plasmid in the bacteria is devoid of the insert (foreign DNA), it will result in the formation of blue-coloured colonies due to the presence of a chromogenic substrate. Whereas the presence of insert results into insertional inactivation of
the β-galactosidase gene and thus it does not code for the enzyme, hence the chromogenic substrate is not acted upon by the enzyme, thus the colonies do not produce any coLour and are identified as recombinant coLonies.

Question 9.
(A) A 4-year-old girl undergone the first gene
therapy in 1990 as shown in the picture below. For which disease she was treated and name the scientists responsible for attempting this successful therapy?

(B) RNA interference is a method of cellular defense in which silencing of a specific mRNA is performed through a complementary RNA molecule that binds to and prevents translation of the mRNA. From where does this complementary RNA come from? (3)
Answer:
(A) In 1990, the first clinical gene therapy was given to a 4-year-old girl suffering from Adenosine Deaminase (ADA) deficiency by Michael Blease and W. French Andreson of National Institute of Health.

Related Theory
The enzyme adenosine deaminase is very important for the immune system to function. The cause of the disorder is deletion of the gene coding for adenosine deaminase.
(B) This complementary RNA can come from:
(i) An infection by viruses having RNA genomes.
(ii) Mobile genetic elements (transposons) that replicate via an RNA intermediate.

Question 10.
(A) The given picture shows the antigen- antibody reaction. Name a technique based on the principle of antigen- antibody reaction used in the detection of a virus.

(B) It was an amazing discovery in the field of biotechnology that bacterium Bacillus thuringiensis produces a toxin that can kill insects belonging to a particular group. But the bacteria itself do not get killed by the toxin it produces. Explain the major reason behind this? (3)
Answer:
(A) The technique that is based on the principle of antigen-antibody interaction and used in the detection of a virus is Enzyme-Linked Immunosorbent Assay (ELISA).

Related Theory
Antigen-antibody interaction refers to a specific chemical interaction between antibodies produced by B-lymphocytes and antigens from any source during an immune reaction. Antibodies recognize specific proteins present on antigen surface. The reaction between antigen and antibody leads to agglutination. ELISA can be used to detect an antibody to HIV.

(B) Bacillus thuringiensis forms protein crystals during a particular phase of their growth. A toxic insecticidal protein is present in these crystals. But the bacterium itself is not affected or killed by this toxin because the BT toxin protein exist as inactive protoxins, but when an insect feed on such a plant and ingest the inactive toxin, the protoxin gets converted into an active form due to the alkaline pH of the gut, that solubilize the crystals. The activated toxin binds to the surface of midgut epithelial cells and make it porous resulting in cell swelling and lysis and finally cause death of the insect.

Question 11.
(A) Parasites are well adapted to survive inside the body of their respective hosts. Enlist any two adaptive features evolved in parasites that enable them to survive successfully in or on their hosts.
(B) Among all the abiotic factors that influences life of organisms, why temperature is considered to be the most relevant factor? (3)
Answer:
(A) Parasites have evolved special adaptations that enable them to survive successfully, in or on their hosts they are:

• Loss of unnecessary sense organs.
• Presence of adhesive organs or suckers to cling on to the host.
• Loss of digestive system.
• High reproductive capacity. (Any two)

(B) Temperature is an important ecologically
environmental factor that affects the different aspects of the living organism. Different types of physiological activities such as enzymatic activities as well as geographical distribution of different species depends on the temperature conditions and levels of their thermal tolerance. Therefore, the living organism is required to maintain specific internal temperatures.

Related Theory
Temperature influences the distribution of species as the species are able to grow within a narrow range of temperature which is known as the optimum temperature. The organisms are able to survive by maintaining all biological processes within an optimum temperature. The primary factors that affect the organisms are temperature, water, humidity, p^H.

Question 12.
The available species inventories to estimate the global species diversity do not include the diversity of prokaryotic species. The biologists are still unaware of the total prokaryotic diversity. Why? Give reasons. (3)
Answer:
Biologists are still unaware of the total prokaryotic diversity because of the following reasons:

• The conventional taxonomic methods are not suitable for identifying microbial species.
• Many microbial species cannot be cultured under laboratory conditions.
• If biochemical or molecular criteria for delineating microbial species is accepted and followed, then their diversity alone might run into millions.

SECTION – C
(Section C has a case-based question of 5 marks.)

Question 13.
A school student trip was organized and students were taken to a sewage treatment plant, where the students observed the treatment of sewage before it can be discharged into rivers.
Based on this, answer the following questions:

(A) What do you mean by waste water?
(B) Why reduction in BOD is required in the treatment of sewage water?
(C) The process which involves removal of large and small particles through filtration and sedimentation is called as?
(D) State two advantages of sewage treatment plants.
OR
Rekha observed the following pictures of microbes showing virus and bacteria. On seeing these pictures, it reminded her of the beginning of the Covid-19 pandemic. She started cursing microbes as she thought that they are a curse on this earth. But her teacher told her that all the microbes are not harmful for us. Microorganisms are very useful as they provide various medicines, household products, bioactive molecules, etc.

Based on this answer the following questions:

(A) (i) Apart from making curd, what is the function of microbe Lactobacillus1
(ii) Name any two enzymes produced by microbes that are used for clarification of bottled juices.

(B) (i) Name the fungus from which first antibiotic was isolated.
(ii) Write any two roles served by Saccharomyces cerevisiae. (5)
Answer:
(A) Waste water is the water that is produced after the use of fresh water by human beings for variety of applications such as domestic, commercial and industrial use.

(B) The greater the BOD of sewage water, more is its polluting potential. So, the sewage water is treated, till its BOD is reduced to reduce the organic matter present in it.

(C) The process which involves removal of large and small particles through filtration and sedimentation is called as primary treatment of sewage.

(D) The advantages of sewage treatment plants (STPs) are:
(i) STPs preserve natural environment against pollution.
(ii) STPs eliminate disease-causing bacteria and kills harmful organisms from the sewage water before its discharge into the rivers. In this way, STPs reduces risk to public health and the environment.
OR
(A) (i) Lactobacillus increases the nutritional value of the curd by increasing the amount of vitamin B₁₂ in it.
(ii) Two enzymes produced by microbes that are used for clarification of bottled juices are pectinase and protease.

(B) (i) The fungus/mould from which first antibiotic was isolated was Penicillium notatum.
(ii) Two roles of Saccharomyces cerevisiae are:
(i) It is used in bread making.
(ii) It is used in the commercial production ofethanoL
Related Theory
Saccharomyces cerevisiae is also known as baker’s and brewer’s yeast.

Students can access the CBSE Sample Papers for Class 12 Geography with Solutions and marking scheme Term 2 Set 7 will help students in understanding the difficulty level of the exam.

CBSE Sample Papers for Class 12 Geography Term 2 Set 7 with Solutions

Time Allowed: 2 Hours
Maximum Marks: 35
Roll No. ___________

General Instructions:

• Question paper is divided into 5 sections A, B, C, D & E
• In section A, question number 1 to 3 are Very Short Answer type questions. Attempt any 3 questions.
• In section B, question number 4 is Source based question.
• In section C, question number 5 & 6 are Short Answer type questions.
• In section D, question number 7 to 9 are Long Answer type questions.
• In section E, question number 10 is a Map based question.

Section – A
Very Short Answer Questions

Question 1.
How does consumer cooperatives, departmental stores contribute to trade and commerce in a region? (2)
Or
Explain the different factors that affect transport.
Answer:
Consumer cooperatives and departmental stores contribute to trade and commerce in a region in following ways

• Consumer cooperatives were the first of the large-scale innovations in retailing.
• Departmental stores delegate the responsibility and authority to departmental heads for purchasing of commodities and for overseeing the sale in different sections of the stores.

Or
There are two important factors that affect transport

• Demand for Transport It is influenced by the size of population. The larger the population size, the greater is the demand for transport
• Routes It depends on location of cities, towns, villages, industrial centres and raw materials, pattern of trade between them, nature of the landscape between them, type of climate, and funds available for overcoming obstacles along the length of the route.

Question 2.
Briefly describe the steps taken by the Indian railways to revolutionise rail transport (2)
Answer:
A few steps taken by Indian railways to revolutionise rail transport are

• Indian Railways has launched extensive programme to convert the metre and narrow gauges to broad gauge.
• Moreover, steam engines have been replaced by diesel and electric engines. This step has increased the speed, as well as, the haulage capacity.

Question 3.
Define air pollution and its sources. (2)
Answer:
Air pollution is the addition of contaminants, like dust, fumes, gas, fog, odour, smoke or vapour to the air in substantial proportion and duration that may be harmful to flora and fauna and to property. Combustion of fossil fuels, mining and industries are the main sources of air pollution These processes release oxides of sulphur and nitrogen, hydrocarbons, carbon dioxide, carbon monoxide, lead and asbestos.

Section – B
Source Based Question

Question 4.
Read the source given below and answer the following questions by choosing the correct option.
Bio-energy refers to energy derived from biological products which includes agricultural residues, municipal, industrial and other wastes. Bioenergy is a potential source of energy conversion. It can be converted into electrical energy, heat energy or gas for cooking.

It will also process the waste and garbage and produce energy. This will improve economic life of rural areas in developing countries, reduce mental pollution, enhance self-reliance and reduce pressure on fuel wood. One such project converting municipal waste into energy is Okhla in Delhi.

The challenge of sustainable development requires integration of quest for economic development with environmental concerns. Traditional methods of resource use result into generating enormous quantity of waste as well as create other environmental problems. Hence, for sustainable development calls for the protection of resources for the future generations.

There is an urgent need to conserve the resources. The alternative energy sources like solar power, wind, wave, geothermal energy are inexhaustible resource. These should be developed to replace the exhaustible resources. In case of metallic minerals, use of scrap metals will enable recycling of metals. Use of scrap is specially significant in metals like copper, lead and zinc in which India’s reserves are meagre. Use of substitutes for scarce metals may also reduce their consumption. Export of strategic and scarce minerals must be reduced, so that the existing reserve may be used for a longer period.

i. What are the economic implications of bio-energy for rural community? (1)
Answer:
Economic implications of bio energy for rural community are reducing reliance on fuel wood, increasing availability of non-wood energy and reducing environmental damage and associated cost.

ii. Why do we need alternatives to conventional fuel resources such as fossil fuels? (1)
Answer:
We need alternatives to conventional fuel resources such as fossils fuels because conventional fuel resources led to pollution.

iii. Why should export of rare and scarce minerals be reduced? (1)
Answer:
Export of rare and scare minerals should be reduced for extended use of existing reserves in a region.

Section – C
Short Answer Questions

Question 5.
Explain agro based industries and agri-business. (3)
Or
What do you mean by large integrated industry and mini-steel mills. Outline the distribution of iron and steel industry in Asia.
Answer:
Agro-based Industries involves the processing of raw materials from the field and the farm into finished products for rural and urban markets. Major agro-processing industries are food processing, sugar, pickles, fruits juices, beverages (tea, coffee and cocoa), spices and oils fats and textiles (cotton, jute, silk), rubber, etc.

Agro processing includes carning producing cream, fruit processing and confectionery, While some preserving techniques, such as drying, fermenting and pickling, have been known since ancient times, these had limited applications to cater to the pre-Industrial Revolution demands.

Agri-business is commercial farming on an industrial scale often financed by business whose main interests lie outside agriculture, for example, large corporations in tea plantation business. Agri-business farms are mechanised, large in size, highly structured, reliant on chemicals, and may be described as ‘agro-factories’.
Or
The large integrated steel industry is traditionally located close to the sources of raw materials which are iron ore, coal, manganese and limestone or at places where these could be easily brought, e.g. near ports. On the other hand in mini steel mills, access to markets is more important than inputs. These are less expensive to build and operate and can be located near markets because of the abundance of scrap metal, which is the main input.

Traditionally, most of the steel was produced at large integrated plants, but mini mills are limited to just one-step process steel making, and are gaining ground. In Asia, the important centres of iron and steel industry include Nagasaki and Tokyo-Yokohama in Japan; Shanghai, Tienstin and Wuhan in China; and Jamshedpur, Kulti-Burpur, Durgapur, Rourkela, Bhilai, Bokaro, Salem, Visakhapatnam and Bhadravati in India.

Question 6.
Write a detailed note on Geothermal energy. (3)
Answer:
Geothermal energy is the head energy within the earth. When the magma from the interior of earth, comes out on the surface, tremendous heat is released. This heat energy can successfully be tapped and converted to electrical energy. Apart from this, the hot water that gushes out through the geyser wells is also used in the generation of thermal energy.

This energy is now considered to be one of the key energy sources which can be developed as an alternate source. The hot springs and geysers are being used since medieval period. In India, a geothermal energy plant has been commissioned at Manikaran in Himachal Pradesh.

Section – D
Long Answer Questions

Question 7.
A basic industry is responsible for providing raw material to other industries. They are important for a nation’s economy. Discuss the role of iron and steel industry as a basic industry and location of steel industries. Also explain about production of iron. (5)
Or
Elucidate the structure and distribution of cotton textile industries in the world.
Answer:
The iron and steel industry forms the base of all other industries and, therefore, it is called a basic industry. It is basic because it provides raw material for other industries such as machine tools used for further production and for building infrastructure in industries, transportation and residential settlements. It may also be called a heavy industry because it uses large quantities of bulky raw materials and its products are also heavy.

The large integrated steel industry is traditionally located close to the sources of raw materials i.e. iron ore, coal, manganese and limestone or at places where these could be easily brought, e.g. near ports. But in mini steel mills access to markets is more important than inputs. These are less expensive to build and operate and can be located near markets because of the abundance of scrap metal, which is the main input.

Traditionally, most of the steel was produced at large integrated plants, but mini mills are limited to just one-step process i.e. steel making Iron is extracted from iron ore by smelting in a blast furnace with carbon (coke) and limestone. The mineral ores commonly used for iron production are hematite and magnetite. Naturally, iron ores are found in Banded Iron Formations (BIFs) which are sedimentary rocks of Precambrian.

The molten iron is cooled and moulded to form pig iron which is used for converting into steel by adding strengthening materials like manganese. Cotton is the world’s most important fibre which is used for production of several products including textiles. Cotton textile industry has three sub-sectors i.e. handloom, powerloom and mill sectors

1. Handloom sector is labour-intensive and provides employment to semi-skilled workers. It requires small capital investment. This sector involves spinning, weaving and finishing of the fabrics.
2. The powerloom sector introduces machines and becomes less labour intensive and the volume of production increases.
3. Cotton textile mill sector is highly capital intensive and produces fine clothes in bulk.

Cotton textile manufacturing requires good quality cotton as raw material. Cotton textile industries produces two types of products, i.e. cotton yarn and cotton cloth. These industries are spread globally in over 90+ countries, however India, China, USA, Pakistan, Uzbekistan and Egypt produce more than half of the world’s raw cotton China and India also lead the global production of cotton yarn and cloths. The UK, NW European countries and Japan also produce cotton textile made from imported yarn. Europe alone accounts for nearly half of the world’s cotton imports.

Question 8.
State the global distribution of railways in the continents of the world. (5)
Answer:
The global distribution of railways in the world is

Europe has one of the most dense rail networks in the world. There are about 4,40,000 km of railways, most of which is double or multiple-tracked. The important rail heads are London, Paris, Brussels, Milan, Berlin and Warsaw. Passenger transport is more important than freight in many of these countries.

In Russia, railways account for about 90 percent of the country’s total transport with a very dense network west of the Urals. Moscow is the most important rail head with major lines radiating to different parts of the country’s vast geographical area.

North America has one of the most extensive rail networks accounting for nearly 40 per cent of the world’s total. The railways are used more for long-distance bulky freight like ores, grains, timber and machinery than for passengers. The most dense rail network is found in the highly industrialised and urbanised region of East Central U.S.A. and adjoining Canada.

Australia has about 40,000 km of railways, of which 25 per cent are found in New South Wales alone. The west-east Australian National Railway line runs across the country from Perth to Sydney. New Zealand’s railways are mainly in the North Island to serve the farming areas.

In South America, the rail network is the most dense in two regions, namely, the Pampas of Argentina and the coffee growing region of Brazil which together account for 40 per cent of South America’s total route length. Only Chile, among the remaining countries has a considerable route length linking coastal centres with the mining sites in the interior.

Question 9.
Highlight the importance of roads in land transport. (5)
Answer:
The importance of roads in land transport is

1. Roads in land transport are the most economical for short distances compared to railways.
2. Freight transport by road is important because it offers door-to-door service.
3. Roads play a vital role in a nation’s trade and commerce and for promoting tourism.
4. The quality of the roads varies greatly between developed and developing countries because road construction and maintenance require heavy expenditure.
5. In developed countries good quality roads are universal and provide long-distance links in the form of motorways, autobahns (Germany), and inter-state highways for speedy movement.
6. Lorries, of increasing size and power to carry heavy loads are common.
7. Road transport is most flexible and adaptable with an outreach into the most remote areas that are inaccessible by rail, air or water.

Section – E
Map Based Question

Question 10.
On a political map of India locate and label the following features (Attempt any 5). (1 × 5 = 5)
(i) Bokaro coal mines
(ii) Important town of Golden Quadrilateral in the North
(iii) Northernmost node in the North-South Corridor
(iv) Balaghat manganese mines
(v) Khetri copper mines
(vi) Barauni oil refinery
Answer:

Students can access the CBSE Sample Papers for Class 12 Chemistry with Solutions and marking scheme Term 2 Set 9 will help students in understanding the difficulty level of the exam.

CBSE Sample Papersn for Class 12 Chemistry Term 2 Set 9 with Solutions

Time Allowed: 2 Hours
Maximum Marks: 35

General Instructions:

• There are 12 questions in this question paper with internal choice.
• SECTION A – Q. No. 1 to 3 are very short answer questions carrying 2 marks each.
• SECTION B – Q. No. 4 to 11 are short answer questions carrying 3 marks each.
• SECTION C- Q. No. 12 is case based question carrying 5 marks.
• All questions are compulsory.
• Use of log tables and calculators is not allowed.

Section – A
(Section A-Question No 1 to 3 are very short answer questions carrying 2 marks each.)

Question 1.
Explain what is observed:
(A) When a beam of light is passed through a colloidal solution.
Answer:
When a beam of light is passed through a colloidal solution, the path of the beam gets illuminated by bluish light and this is known as Tyndall effect.

(B) Electric current is passed through solution. (2)
Answer:
When the electric current is passed through colloidal solution movement of the colloidal particles either towards the cathode or towards the anode takes place. This is known as electrophoresis. Explanation: The Tyndall effect is the phenomenon in which the particles in a colloid scatter the beams of light that are directed at them. This effect is exhibited by all colloidal solutions and some very fine suspensions. Thus the identity of the colloidal solutions is determined by this effect. The density of the colloidal particles as well as the frequency of the incident light determines the intensity of the colloidal solutions.

Question 2.

Observe the above graph and explain the variation of conductivity with concentration for strong and weak electrolyte. (2)
Answer:
Variation of conductivity depends on the concentration of the electrolyte. The conductivity and Molar conductivity of both weak and strong electrolytes decreases with decrease in concentration as the number of ions per unit volume carrying the current in a solution decreases on dilution.

For strong electrolytes number of ions per unit volume are high as they completely dissociate in solution. With dilution the interionic forces decrease therefore ionic mobility increases.
For weak electrolytes extent of dissociation is very small and with dilution the dissociation increases slowly but the value of molar conductivity at infinite dilution cannot be obtained as in the case of strong electrolyte.

Question 3.
Carry out the following conversions: (Any two)
(A) Methyl chloride to Acetic acid
Answer:

(B) Benzene to benzoic acid
Answer:

(C) Ethanol to Acetone. (2)
Answer:

Section – B
(Section B-Question No 4 to 11 are short answer questions carrying 3 marks each.)

Question 4.
(A) Calculate the rate of the reaction for the rate law -d[A]/ dt = K [A].[B]², when the concentration of A and B are 0.1 M and 0.02 M respectively and K = 5.1 × 10^-3 L² s^-1 mol^-2.
(B) What is the order of the reaction for the graph given below, What does the slope depict for a graph between In [A] and time. (3)

Answer:
(A) Given that
Rate of reaction
\(\frac{\mathrm{d}[\mathrm{A}]}{\mathrm{dt}}\) = K [A], [B]²

Given K = 5.1 × 10^-3 L²s^-1 mol^-1
[A] = 0.1 M, [B] = 0.02 M, then
– \(\frac{\mathrm{d} \mathrm{A}}{\mathrm{dt}}\) = 5.1 × 10^-3 × 0.1 × (0.02)²
= 0.00204 × 10^-3
= 2.04 × 10^-7 Ms^-1

(B) For first-order reactions, the equation ln[A] = -kt + ln[A]₀ is similar to that of a straight line. (y = mx + c) with slope -k. Thus, the graph for ln[A] v/s t for a first-order reaction is a straight line with slope -k

Question 5.
(A) Differentiate between physical and Chemical Adsorption.
(B) What does the following graph depict about adsorption.

OR
Give reason for the following:
(A) Finely divided substances are more effective as adsorbents.
(B) Lyophilic colloids are also called reversible sols.
(C) Agl sol, formed after AgNO₃ reacts with Kl, is negatively charged. (3)
Answer:
(A)

(B) The Freundlich equation or Freundlich adsorption isotherm is shown in the graph and adsorption isotherm, is an empirical relation between the concentration of a solute on the surface of an adsorbent to the concentration of the solute in the liquid with which it is in contact.
OR
(A) The finely divided substance is more effective as an absorbent because more the surface area more is the extent of adsorption. So they act as good adsorbents.

(B) Lyophilic colloids are also called reversible sols because once separated these can be reformed by simple mixing. Thus due to this reversible property they are also regarded as reversibel sols.

(C) When silver nitrate (AgNO₃) solution is added to Kl solution, a negatively charged sol is formed. It is due to the preferential adsorption of I_– ions and thus the Agl sol formed is negatively charged in nature.

Question 6.
(A) Give any two differences between double salts and complexes?
(B) Explain how [FeF₆]^3- is paramagnetic outer orbital complex. (3)
Answer:
(A) The difference between Double salt and Complex compound are:

(B) In [FeF₆]^3-
Oxidation number of Fe = +3
Coordination Number Fe = 6
Coordination orbitals = 6
Fe → Fe³⁺ + 3e^–
Fe³⁺ → (26-3) – [Ar]₁₈
[FeF₆]^3- – (Strongly Paramagnetic)

Here F is a weak field ligand and it obeys Hund’s rule of leaving maximum number of unpaired electrons (n = 5) and it uses one 4s, three 4p and two 4d orbitals which are sp³ d² hybridised. So it is an outer orbital complex.

Question 7.
(A) What is the role of pyridine in the acylation reaction of amines ?
(B) Why is NH₂ group of aniline acetylated before carrying out nitration? Explain with the help of reactions.
OR
Predict the product for the reaction of:
(A) Aniline with bromine in non-polar solvent such as CS₂.
(B) C₆H₅CH₂NH₂ reacts with HNO₂
(C) Reduction of nitriles with LiAlH₄ (3)
Answer:
(A) Pyridine and other bases are used to remove the side product i.e., HCl formed during reaction mixture.

(B) Direct nitration of aniline is not possible on account of oxidation of —NH₂ group. However, nitration can be carried after protecting the —NH₂ group by acetylation to give acetanilide which is then nitrated and finally hydrolysed to give o-and p-nitroanilines.

The acetyl group being electron withdrawing attracts the lone pair of electrons of the N-atom towards carbonyl group.

As a result the activating effect —NH₂ group is reduced i.e., the lone pair of electrons on nitrogen is less available for donation to because to benzene ring by resonance. Therefore, activating effect of the —NHCOCH₃ group is less than that of the — NH₂ group.
OR

(C) Reduction of nitriles with sodium alcohol or LiAlH₄ gives primary amine RNH₂

Question 8.
(A) Decide giving reason which one of the following pairs exhibits the property indicated:
(i) Sc³⁺ or Cr³⁺ (exhibits paramagnetism)
(ii) V or Mn (exhibits more number of oxidation states)
(iii) V⁴⁺ or V⁵⁺ (exhibits colour) (3)
Answer:
(A) Cr³⁺ exhibits parai4iognetism due to the presence of 3 unpaired electrons in 3d orbitals

Explanation:
Electronic configuration
Sc³⁺ : [Ar] 3d° 4s° – No unpaired electron
Cr³⁺ : [Ar] 3d³ 4s° – Three unpaired electrons

(B) Mn shows maximum oxidation states (+2 to +7)
Explanation:
Electronic configuration:
V : [Ar] 3d³ 4s² (5 electrons can participate in bonding)
Mn : [Ar] 3d⁵ 4s² (7 electrons can participate in bonding)

(C) V⁴⁺ shows colour due to the presence of one unpaired electron in 3d orbital which undergoes d-d transition. V⁵⁺ does not have any unpaired electron.

Question 9.
Account for the following observations:
(A) pkb value for aniline is more than that for methylamine.
(B) Methylamine in water reacts with ferric chloride to precipitate ferric hydroxide
(C) Aniline does not undergo Friedel-Craft’s reaction. (3)
Answer:
(A) Aniline undergoes resonance and as a result, the electrons on the N-atom are delocalized over the benzene ring. Therefore, the electrons on the N-atom are less available to donate. In case of methylamine (due to the +1 effect of methyl group), the electron density on the N-atom is increased. As a result, aniline is less basic than methylamine. Thus, pKb of aniline is more than that of methylamine.

(B) Methylamine in water reacts with ferric chloride to precipitate hydrated ferric oxide. Due to the +1 effect of -CH₃ group, methylamine is more basic than water. Therefore, in water, methylamine produces OH- ions by accepting H+ ions from water. OH” ions react with ferric chloride to precipitate hydrated ferric oxide.

(C) Aniline does not undergo Friedel Craft’s reactions because the reagent AlCl₃ (a Lewis acid which is used as a catalyst in Friedel Crafts reaction), being electron deficient acts as a Lewis base, and attacks on the Lone pair of nitrogen present in aniline to form an insoluble complex which precipitates out and the reaction does not proceed.

Question 10.
Give reasons for the following:
(A) Transition elements act as catalysts
(B) It is difficult to obtain oxidation state greater than two for Copper.
(C) CrO is basic but Cr₂O₃ is amphoteric.
OR
Observed and calculated values for the standard electrode potentials of elements from Ti to Zn in the first reactivity series are depicted in following figure:

Explain the following observations:
(A) The general trend towards less negative E°values across the series
(B) The unique behaviour of Copper
(C) More negative E° values of Mn and Zn (3)
Answer:
(A) Due to large surface area and ability to show variable oxidation states Transition elements act as catalysts due to the large surface area and ability to show variable oxidation states.

(B) Due to high value of third ionisation enthalpy. It is difficult to obtain oxidation state greater than two for Copper because the value of third ionisation enthalpy is very high for a copper atom.

(C) Oxidation state of Cr in Cr₂O₃ is +3 and of CrO is +2. When oxidation number of a metal increases, ionic character decreases so CrO is basic while Cr₃O₃ is amphoteric. CrO is basic but Cr₂O₃ is amphoteric because oxidation state of Cr in Cr₂O₃ is +3 and of Cr in CrO is +2. When oxidation number of a metal increases, ionic character decreases so CrO is basic while Cr₂O₃ is amphoteric.
OR
(A) The general trend towards less negative E° values across the series is related to the general increase in the sum of the first and second ionisation enthalpies.

(B) The high energy to transform Cu(s) to Cu²⁺(aq) is not balanced by its hydration enthalpy.

(C) The stability of the half-filled d sub-shell in Mn²⁺ and the completely filled d¹⁰ configuration in Zn²⁺ are related to their more negative E° values.

Question 11.
A 0.25 M KOH solution offered a resistance of 31.6 ohms in a conductivity cell at 298 K. If the cell constant of the conductivity cell is 0.367cm^-1, find out the specific and molar conductance of the potassium hydroxide solution.
OR
Calculate emf and ∆G for the following reaction at 298 K:
Mg_(s)/Mg²⁺(0,01M) // Ag⁺(0.0001)/Ag_(s)
Given E° (Mg²⁺/Mg) = -2.37 V;
E° (Ag⁺/Ag) = +0.80 V (3)
Answer:
Resistance (R) = 31.6 ohm
Conductance (C) = 1/R = 1/31.6 ohm = 0.0316 ohm^-1
Specific Conductance (K ) = Conductance × cell constant
= 0.0316 ohm^-1 × 0.367 cm^-1
= 0.0116 ohm^-1 cm^-1
Molar concentration (C)= 0.25mol/1L = 0.25 mol/10³ cm² = 0.25 × 10^-3 mol cm^-3

MolarConductivity ∧_m = \(\frac{k \times 1000}{c}\)
= \(\frac{0.0116 \times 1000}{0.25 \times 10^{-3}}\)
= 0.0464 × 10⁶
∧_m = 4.64 × 10⁴ Scm^-1 mol^-1
OR
E°_cell = E°_cathode – E°_anode = E°_(Ag+/Ag) – E°_(Mg²⁺
= + 0.80 V – (- 2.37V) = 3.17 V
∆G° = -n F E°cell
= – 2 × 96500 C mol^-1 × 3.17V
= -611810 C mol^-1 = -611810 J mol^-1
= -611.810 1G mol^-1

Section – C
(Section C- Question No 12 is case-based question carrying 5 marks.)

Question 12.
Read the passage given below and answer the following questions:
Oxidation of alcohols to aldehydes is partial oxidation; aldehydes are further oxidized to carboxylic acids. Conditions required for making aldehydes are heat and distillation. In aldehyde formation, the temperature of the reaction should be kept above the boiling point of the aldehyde and below the boiling point of the alcohol. Reagents useful for the transformation of primary alcohols to aldehydes are normally also suitable for the oxidation of secondary alcohols to ketones.

[0] = chromium-based reagent, activated DMSO, hypervalent iodide compound, TRAP or TEMPO
R¹ = alkyl or aryl substituent
R² = hydrogen, alkyl or aryl substituent
(A) Name the reagent which can be used to oxidise an alcohol to a ketone.
(B) Write the aldehyde and the ketone formed by the oxidation of propan-l-ol and propan-2-ol respectively.
(C) Propanal can be oxidized easily than propanone. Give reason.
(D) Give simple chemical tests to distinguish between the following pairs of compounds.
(i) Propanal and Propanone
(ii) Ethanal and Propanal
OR
How will you prepare the following compounds starting with benzene:
(i) Benzaldehyde
(ii) Acetophenone (5)
Answer:
(A) CrO₃ with heat

Caution
If a student writes PCC in place of CrO₃, it will be a wrong answer because PCC (mild oxidizing agent) can be used to oxidise a primary alcohol to an aldehyde.

(B) Proparial and Propanone

Explanation:
Propan-1-ol being a primary alcohol on oxidation gives propanal an oldehyde and Propan-2-ol being a secondary alcohol on oxidation gives propanone.

(C) The difference between an aldehyde and ketone is the presence of a hydrogen atom attached to the carbon-oxygen double bond in the aldehyde. Ketone doesn’t have that hydrogen attached. Due to electron-withdrawing nature of C=O group, C—H bond in aldehyde is weak and thus it can be easily oxidised to corresponding Corboxylic acid.

(D) (i) Propanal. (aldehyde) and propanone (ketone):
Propanol gives sâ.er mirror test with Totten’s reagent. Propanone does not gives this test.

(ii) Ethonal and proponat can be distinguished by Iodoforrn test. Ethanal gives a yellow precipitate of iodofirm with an aLkaline so4ution of NaOH. Propanal does not gives this test.