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Online Education for Class 8 Science Chapter 4 Extra Questions and Answers Materials: Metals and Non-Metals
Materials Metals And Non Metals Class 8 Questions And Answers Question 1.
Do non-metals produce ringing sound?
No, non-metals do not produce the ringing sound. It is a property of metals only.
Materials: Metals And Non Metals Class 8 Questions And Answers Question 2.
List the characteristic properties of metals.
The metals have the following properties :
- sonority, and
- good conductivity of heat and electricity.
Metals And Non Metals Class 8 Question 3.
Name some metals.
Iron, copper, gold, aluminium, magnesium, etc.
Cbse Class 8 Science Metals And Nonmetals Question 4.
Give some examples of non-metals.
Sulphur, carbon, oxygen, phosphorus, calcium, etc.
Metals And Non Metals Class 8 Extra Questions Question 5.
Name two metals which can be cut with knife.
Sodium and potassium are two metals which are soft and can be cut with a knife.
Metal And Non Metals Class 8 Question 6.
Name a metal which is found in liquid state at room temperature.
Materials Metals And Non Metals Questions And Answers Question 7.
Write the equation of rusting of iron.
3Fe + 2H2O + O2 → Fe3O4 + 2H2.
Extra Questions On Metals And Non-Metals Class 8 Question 8.
If the red litmus placed in a solution turns blue, the solution is called hydroxides.
Class 8th Science Chapter 4 Extra Questions Question 9.
If the blue litmus paper turns red, the solution is called hydroxides.
Class 8 Science Ch 4 Extra Questions Question 10.
When sulphur reacts in air (O2), what is the product formed.
It is sulphur dioxide (SO2).
Class 8 Metals And Nonmetals Extra Questions Question 11.
What is formed when sulphur dioxide is dissolved in water? Also, write the equation.
Sulphurous acid is formed.
SO2 + H2O →H2SO3 (Sulphurous acid).
Metal And Non Metal Class 8 Question 12.
What happens when a blue litmus paper is treated with an acid?
The blue litmus paper turns red.
Science Class 8 Metals And Non Metals Question 13.
Name the non-metals in the following acids :
Sulphuric acid (H2SO4), Hydrochloric acid (HCl) and Nitric acid (HNO3).
Sulphur, chlorine and nitrogen respectively.
Materials Metals And Nonmetals Class 8 Questions And Answers Question 14.
What happens when a small piece of sodium metal is placed in water?
The metal piece starts moving in water with a hissing sound and then it catches fire.
Metals And Nonmetals Class 8 Questions Answers Question 15.
Why are metals used in making machinery?
Metals are very hard, can withstand very high temperatures and are strong as well as lustrous. That is why they are used “in making various machinery.
The substances made up of only one type of atoms are called elements. Sulphur, iron, gold, calcium, hydrogen, etc. are elements. There are about 92 elements. Most of the elements are metals.
What is an atom?
An atom is the smallest unit of an element. The atom of an element remains unaffected by any physical change in the element.
Describe how metallic and non-metallic oxides are formed.
On burning, metals react with oxygen to produce metal oxides which are basic in nature. Non-metals react with oxygen to produce non-metallic oxides which are acidic in nature.
How can metals be distinguished from non-metals?
Metals can be distinguished from non-metals on the basis of their physical and chemical properties.
Define malleability of a metallic substance. ‘
The property of metals by which they can be beaten into thin sheets is called malleability. This is the characteristic property of metals.
Why is sodium stored in kerosene?
Sodium metal is very reactive. It reacts vigorously with oxygen and water. A lot of heat is generated in the reaction. Therefore it is stored in kerosene to avoid its contact with air and water.
Explain the construction of a water filter with materials available at home.
(a) Cut off the bottom of a plastic bottle and place the bottle upside down into the vase or tall drinking glass.
(b) Place cotton balls, cloth, or a coffee filter inside the bottle as the first layer. Add an inch of activated charcoal as the second layer. Over the charcoal, add about two inches of small stones as the third layer and add about three to four inches of clean sand on top of the gravel.
(c) Add gravel to the bottle as the final layer. Leave about a half-inch of space from the top of the upside-down bottle.
(d) Pour the glass of muddy water on top of the homemade water filter and watch the water drip clean into the glass below.
How metal reacts with
(b) Water and
(a) Metals react with oxygen and form their oxides.
Magnesium (Mg) + Oxygen (O2) → Magnesium Oxide (MgO)
Sodium (Na) + Oxygen (O2) → Sodium oxide (Na2O)
(b) Metals react with water differently. Metals like sodium reacts with water vigorously and a lot of heat is produced. Whereas iron reacts with water slowly.
Sodium (Na) + Water (H2O) → Sodium hydroxide (NaOH) + Hydrogen gas (H2)
(c) Metals react with dilute acids and produce hydrogen gas that burns with a ‘pop’ sound.
Zinc (Zn) + Hydrochloric acid (HCl) → Sodium chloride (NaCl) + Hydrogen gas (H2).
(a) What is a displacement reaction? Give an example for it.
(b) Which gas is released when acid reacts with a metal?
(a) The chemical reaction in which a more reactive metal displaces/replaces a less reactive metal from its salt solution is called a displacement reaction. But a less reactive metal cannot replace a more reactive metal.
Copper sulphate (CuSO4) + Zinc (Zn) (Blue) → Zinc sulphate (ZnSO4) + Copper (Cu) (Colourless) (Reddish brown)
(b) Hydrogen gas is released when acid reacts with a metal.
Sodium (Na) + Water (H2O) → Sodium Hydroxide (NaOH) + Hydrogen gas (H2).
Write down three uses of metals and two uses of non-metals.
Uses of metals :
- Metals are used in making machinery, automobiles, aeroplanes, trains, satellites and industrial gadgets, etc.
- Metals are used in making cooking utensils, water boilers, etc.
- Metals are used in making decorative arts, jewellery and coins.
- Aluminium foils are used for packaging medicines, chocolates, decorating sweets, wrapping food, etc.
Uses of non-metals :
- Non-metal essential for our life which all living beings inhale during breathing.
- Non-metals used in fertilisers to enhance the growth of plants.
- Non-metal used in water purification process.
- Non-metals used in crackers.
Multiple Choice Questions (MCQs)
1. Which is the industry responsible for corrosion of marble of the Taj Mahal?
(a) Textile industry
(b) Paper industry
(c) Steel industry
(d) Oil refinery.
(d) Oil refinery.
2. Name the suffocating and corrosive gas.
(a) Carbon dioxide
(b) Sulphur dioxide
(b) Sulphur dioxide.