MCQ Questions for Class 11 Chemistry Chapter 1 Some Basic Concepts of Chemistry with Answers

Answer: (d) 26.7
Explanation:
Atomic weight = (Equivalent weight × Valency)
=(8.9 × 3) = 26.7
(Valency = (26.89)/(8.9) ≈ 3).

Answer: (b) 0.5
Explanation:
The molar mass of
¹²C is 12.0 gmol^-1.
N_A (Avogadros number = 6.022×10²³)
¹²C atoms have a mass of 12.0 g.
Given that: – 6.0 g.
Thus (6.0 g)/ (12.0 gmol^-1) = 0.50 mol.

Answer: (b) 0.2 M
Explanation:
0.1 M AgNO_A will react with 0.1 M NaCl to form 0.1 M NaNO_A.
But as the volume is doubled, conc. of NO^–₃ = \(\frac { (0.1) }{ (2) } \)
= 0.05 M

Answer: (a) Anion
Explanation:
A charged particle, also called an ion, is an atom with a positive or negative charge.
This happens whenever something called an ionic bond forms.
Two particles that have different numbers of electrons (the smallest particle in an atom which is negative) start reacting to each other.
The particle that has the greater amount of electrons takes the other particles electrons.
One becomes positive because it lost an electron, and the other negative because it got another electron.
The two particles become attracted to each other and mix together, making a new kind of particle.

Answer: (c) Kg/m²
Explanation:
Pressure is force per unit area so Kg/m² cannot be a unit of pressure.

Answer: (d) 3.0 N
Explanation:
H₃PO₄ is tribasic
So N = 3M
= 3 × 1 = 3.

Answer: (c) Three Mole
Explanation:
Molecular weight of
CaCl₂ = 111g/mol
Ions in one calcium chloride molecule = Ca⁺² + 2Cl^– = 3 ions
Now no. of molecules in 111g/mol of CaCl₂ = Avogadros number
= 6.02 × 10²³ molecules
So number of ions in 111g/mol of CaCl₂
= 3 × 6.02 × 10²³ ions
= 3 moles.

Answer: (c) One mole of sodium

Answer: (b) 20 ml
Explanation:
NH₃(g) + HCl(g)→ NH₄Cl(s)
t = 0 40ml 0
t = t 20ml solid
Final volume = 20ml.

Answer: (c) CH₃O
Explanation:

Answer: (c) Pb²⁺
Explanation:
Atom in highest oxidation state can oxidize iodide to liberate I₂ which is volumetrically measured by iodometric titration using hypo.
2I^– →I₂
Pb⁺² → Lowest oxidation state cannot oxidise iodide to I₂

Answer: (c) 0.05 M
Explanation:
0.1M AgNO₃ will react with 0.1M NaCl to form 0.1M NaNO₃.
But as the volume doubled, conc. of NO^–₂
= 0.12
= 0.05 M

Answer: (b) 0.5
Explanation:
The molar mass of
¹²C is 12.0 gmol^-1.
N_A (Avogadros number = 6.022 × 10²³)
¹²C atoms have a mass of 12.0 g.
Given that: – 6.0 g.
Thus (6.0 g)/ (12.0 gmol^-1) = 0.50 mol.

Answer: (b) 8.0 g Methane
Explanation:
6g carbon
Moles of carbon = (6/12) = 0.5 mol
Number of carbon atoms
= 0.5 × N_A =0.5N_A (N_A is Avogadro number)
6g ethane (C₂H₆ two atoms of C per mole)
Moles = (6/30) = 0.2 mol
Number of carbon atoms = 0.2 × 2 × N_A = 0.4 N_A
(Number of carbon atoms = moles of compound × number of C atoms per mol × Avogadro number)
8g methane (CH₄)
Moles = (8/16) = 0.5 mol
Number of carbon atoms = 0.5 × 1 × N_A = 0.5 N_A
21g propane (C₃H₈)
Moles = (21/44) =0.48 mol
Number of carbon atoms = 0.48 × 3 × N_A = 1.44 N_A
28g CO
Moles = (28/28) =1 mol
Number of carbon atoms = 1 × 1 × N_A = N_A

Answer: (b) 5
Explanation:
As we know that all non-zero unit are significant number.

Answer: (c) Atomicity
Explanation:
Symbol of an element represents the name along with the number of same atoms in room condition, which is its atomicity, of that element.

Answer: (d) 3.0 N
Explanation:
H₃PO₄ is tribasic
So N = 3M
= 3 × 1 = 3.

Answer: (c) One mole of sodium

Answer: (c) 24.3
Explanation:
As the given sulphate is isomorphous with ZnSO₄.7H₂O its formula would be MSO₄.7H₂O.m is the atomic weight of M, molecular weight of MSO₄.7H₂O
= (m + 32 + 64 + 126) = (m + 222)
Hence % of M= [(m)/ (m+222)] × 100 = 9.87(given)
Or
100 m = (9.87 m + 222 × 9.87)
Or 90.13 m = (222 × 9.87)
Or m = (222 × 9.87)/(90.13)
= 24.3.

Answer: (a) Kelvin
Explanation:
The SI unit of temperature is the Kelvin. Although the Celsius temperature scale is also used, it is considered a derived SI unit and is generally used to measure everyday temperatures.

In the Kelvin scale, the lowest possible temperature is 0 K. This reading is called absolute zero; however, nothing could possibly ever reach this temperature. Absolute zero, according to the Celsius scale, is approximately minus 273 degrees Celsius. Water boils at 373 Kelvin and freezes at 273 Kelvin.

Scientists discovered absolute zero when they figured that as temperature decreases, the volume of a gas also gets smaller. They graphed this relationship and found that for each substance tested, zero volume for each substance would hypothetically occur around minus 273 degrees Celsius, the equivalent of absolute zero.