CBSE Class 11 Chemistry Some Basic Concepts of Chemistry MCQs Set B

Question: Volume of a gas at NTP is 1.12×10⁻⁷ cc. The number of molecule in it is :
a) 3.01×10¹²
b) 3.01×10¹⁸
b) 3.01×10²⁴
d) 3.01×10³⁰
Answer: a

Question: The reaction of calcium with water is represented by the equation Ca + 2H₂O → Ca(OH)₂ + H₂ What volume of H₂ at STP would be liberated when 8 gm of calcium completely eacts with water?
a) 0.2 cm³
b) 0.4 cm³
c) 2240 cm³
d) 4480 cm³
Answer: d

Question: The weight of NaCl decomposed by 4.9g of H₂SO₄, if 6 g of sodium hydrogen sulphate and 1.825 g of HCl, were produced in the reaction is:
a) 6.921 g
b) 4.65 g
c) 2.925 g
d) 1.4 g
Answer: c

Question: 4 g of a hydrated crystal of formula A.xH₂O has 0.8 g of water. If the molar mass of the anhydrous crystal (a) is 144 g mol^–1, The value of x is
a) 4
b) 1
c) 2
d) 3
Answer: c

Question: A solution of 20.2 g of 1,2-dibromopropane in MeOH upon heating with excess Zn produces 3.58 g of an unsaturated compound X. The yield (%) of X is closest to [Atomic weight of r is 80]
a) 18
b) 85
c) 89
d) 30
Answer: b

Question: The weight of a single atom of oxygen is :
a) 1.057 × 10²³ g
b) 3.556 × 10²³ g
c) 2.656 × 10^–23 g
d) 4.538 × 10^–23 g
Answer: c

Question: 1021 molecules are removed from 200 mg of CO₂. The moles of CO₂ left are :
a) 2.88 ×10×⁻³
b) 28.8×10×⁻³
c) 288×10×⁻³
d) 28.8×10³
Answer: a

Question: Which has the maximum number of molecules among the following ?
a) 44 g CO₂
b) 48 g O₃
c) 8 g H₂
d) 64 g SO₂
Answer: c

Question: The molarity of H₂SO₄ solution, which has a density 1.84 g/cc. at 35° C and contains 98% by weight, is :
a) 1.84 M
b) 18.4 M
c) 20.6 M
d) 24.5 M
Answer: b

Question: Sulphur forms the chlorides S₂Cl₂ and SCl₂. The equivalent mass of sulphur in SCl₂ is
a) 8 g/mol
b) 16 g/mol
c) 64.8 g/mol
d) 32 g/mol
Answer: b

Question: The weight of one molecule of a compound of molecular formula C₆0H₁₂₂ is
a) 1.2 × 10^–20 g
b) 5.025 × 10²³ g
c) 1.4 × 10^–21 g
d) 6.023 × 10^–20 g
Answer: c

Question: The normality of solution obtained by mixing 10 ml of N/5 HCI and 30 ml of N/10 HCl is :
a) N /15
b) N /5
c) N /7.5
d) N /8
Answer: d

Question: The normality of orthophosphoric acid having purity of 70 % by weight and specific gravity 1.54 is :
a) 11 N
b) 22 N
c) 33 N
d) 44 N
Answer: c

Question: A solution is prepared by dissolving 24.5 g of sodium hydroxide in distilled water to give 1 L solution. The molarity of NaOH in the solution is
a) 0.2450 M
b) 0.6125 M
c) 0.9800 M
d) 1.6326 M
Answer: b

Question: The oxide of an element contains 67.67% oxygen and the vapour density of its volatile chloride is 79. Equivalent weight of the element is:
a) 2.46
b) 3.82
c) 4.36
d) 4.96
Answer: b

Question: For preparing 0.1 N solution of a compound from its impure sample of which the percentage purity is known, the weight of the substance required will be
a) less than the theoretical weight
b) more than the theoretical weight
c) same as the theoretical weight
d) none of the options
Answer: b

Question: 5.0 g of a certain element X forms 10.0 g of its oxide having the formula X₄O₆. The atomic mass of X is
a) 12.0 amu
b) 24.0 amu
c) 30.0 amu
d) 32.0 amu
Answer: b

Question: The empirical formula of a compound is CH₂O. Its molecular weight is 180. The molecular formula of compound is :
a) C₄HO₄
b) C₃H₆O₆
c) C₆H₁₂O₆
d) C₅H₁₀O₅
Answer: c

Question: Which of the following pairs of solutions are expected to be isotonic, temperature being the same?
a) 0.1 M glucose and 0.1M C₆H₅N+H₃Cl–
b) 0.1 M NaCl and 0.05 M BaCl₂
c) 0.1 M Na₂SO₄ and 0.1 M KNO₃
d) 0.1 M BaCl₂ and 0.075 M FeCl₃
Answer: d

Question: During electrolysis of water the volume of O₂ liberated is 2.24 dm³. The volume of hydrogen liberated, under same conditions will be
a) 2.24 dm³
b) 1.12 dm³
c) 4.48 dm³
d) 0.56 dm³
Answer: c

Question: 0.4 moles of HCl and 0.2 moles of CaCl₂ were dissolved in water to have 500 mL of solution, the molarity of Cl– ion is:
a) 0.8 M
b) 1.6 M
c) 1.2 M
d) 10.0 M
Answer: b

Question: Volume of water needed to mix with 10 mL 10N HNO₃ to get 0.1 N HNO₃ is :
a) 1000 mL
b) 990 mL
c) 1010 mL
d) 10 mL
Answer: b

Question: In a hydrocarbon, mass ratio of hydrogen and carbon is 1:3, the empirical formula of hydrocarbon is
a) CH₄
b) CH₂
c) C₂H
d) CH₃
Answer: a

Question: An aqueous solution of 6.3 g of oxalic acid dihydrate is made up to 250 ml. The volume of 0.1 N NaOH required to completely neutralise 10 ml of this solution is
a) 20 ml
b) 40 ml
c) 10 ml
d) 4 ml
Answer: b

Question: 60 gm of an organic compound on analysis is found to have C = 24 g, H = 4 g and O = 32 g. The empirical formula of compound is:
a) CH₂O
b) CHO
c) C₂H₂O
d) C₂H₂O₂
Answer: a

Question: The vapour density of a mixture containing NO₂ and N₂O4 is 27.6. Mole fraction of NO₂ in the mixture is
a) 0.8
b) 0.6
c) 0.4
d) 0.2
Answer: a

Question: Temperature does not affect :
a) Molality
b) Formality
c) Molarity
d) Normality
Answer: a

Question: The molar concentration of 20 g of NaOH present in 5 litre of solution is :
a) 0.1 moles/litre
b) 0.2 moles/litre
c) 1.0 moles/litre
d) 2.0 moles/litre
Answer: a

Question: Calculate the normality of 10 volume H₂O₂ ?
a) 1.7 N
b) 12 N 
c) 30.3 N
d) 0.0303 N
Answer: a

Question: Arrange the following in the order of increasing mass (atomic mass: O = 16, Cu = 63, N = 14)
I. one atom of oxygen
II. one atom of nitrogen
III. 1 × 10^–10 mole of oxygen
IV. 1 × 10^–10 mole of copper
a) II < I < III < IV
b) I < II < III < IV
c) III < II < IV < I
d) IV < II < III < I
Answer: a