Mole Concept Multiple Choice Questions and Answers

1 How many gm moles oxygen are there in 88 gms carbon di oxide?

A 1

B 2

C 3

D 4

Answer: 4

2 What is the average molecular weight of a gas containing 20% N2 (molecular wt. = 28) and 80% SO2 (molecular wt. = 64)?

A 28.4

B 56.8

C 24.4

D 48.8

View Answer

Answer: 56.8

3 Two statements are given as

(1) When a percentage of fractions is given for gas, it is assumed that it refers to a mole fraction

(2) When a percentage of fractions is given for liquid or solid, it is assumed that it refers to the weight fraction

True statements are

A 1

B 2

C Both 1 and 2

D Neither 1 nor 2

View Answer

Answer: 2

4 What is the formula for a solid compound that contains 42.11% C, 51.46% O, and 6.43% H and having molecular weight about 341.

A C10 O12H29

B C11O13 H

C C12O11H22

D C12O10H37

View Answer

Answer: C12O11H22

5 Select the correct statement

A 1 mole of SO2 and 64 g of Ethyl Chloride have same number of moles

B 1 mole of SO2 and 64 g of Ethyl Chloride don`t have same molecular weights

C Both a and b

D Neither a nor b

View Answer

Answer: 1 mole of SO2 and 64 g of Ethyl Chloride have same number of moles

6 What will be the molecular weight of a chemical, consisting 2 moles of H2SO4, 3 moles of SO2 and 1 mole of NaOH?

A 128

B 228

C 328

D 428

View Answer

Answer: 428

7 If Avogadro number NA, is changed from 6.022 x 1023 mol-1 to 6.022 x 1020 mol-1 this would change

A the definition of mass in units of grams

B the mass of one mole of carbon

C the ratio of chemical species to each other in a balanced equation

D None of the above

View Answer

Answer: the mass of one mole of carbon

8 20.0 g of a magnesium carbonate sample decomposes on heating to give carbon dioxide and 8.0 g magnesium oxide. What will be the percentage purity of magnesium carbonate in the sample? (Atomic weight of Mg = 24)

A 75

B 96

C 60

D 84

View Answer

Answer: 84

9 The number of water molecules is maximum in

A 18 molecules of water

B 1.8 g of water

C 18 g of water

D 18 moles of water

View Answer

Answer: 18 moles of water

10 1.0 g of magnesium is burnt with 0.56 g O2 in a closed vessel. Which reactant is left in excess and how much? (At. wt: Mg=24; O=16)

A Mg, 0.16 g

B O2, 0.16 g

C Mg, 0.44 g

D O2, 0.28 g

View Answer

Answer: Mg, 0.16 g

11 How many grams of concentrated nitric acid solution should be used to prepare 250 mL of 2.0M HNO3? The concentrated acid is 70% HNO3.

A 45.0 g conc.HNO3

B 90.0 g conc.HNO3

C 70.0 g conc.HNO3

D 54.0 g conc.HNO3

View Answer

Answer: 45.0 g conc.HNO3

12 25.3 g of Sodium carbonate Na2CO3 is dissolved in enough water to make 250 mL of solution. If sodium carbonate dissociates completely, molar concentration of sodium ion, Na+ and carbonate ion CO2−3 are respectively (Molar mass of Na2CO3 = 106 g mol-1)

A 0.955 M and 1.910 M

B 1.910 M and 0.955 M

C 1.90 M and 1.910 M

D 0.477 M and 0.477 M

View Answer

Answer: 1.910 M and 0.955 M

13 What is the [OH-] in the final solution prepared by mixing 20.0 mL of 0.050 M HCl with 30.0 mL of 0.10 M Ba(OH)2?

A 0.10 M

B 0.40 M

C 0.0050 M

D 0.12 M

View Answer

Answer: 0.10 M

14 10 g of hydroen and 64g of oxygen were filled in a steel vessel and exploded. Amount of water produced in this reaction will be

A 2 mol

B 3 mol

C 4 mol

D 1 mol

View Answer

Answer: 4 mol

15 Volume occupied by one molecule of water (density = 1g cm-3) is

A 9.0 x 10-23 cm3

B 6.023 x 10-23 cm3

C 3.0 x10-23 cm3

D None of these

View Answer

Answer: 3.0 x10-23 cm3

16 Concentrated aqueous sulphuric acid is 98% H2SO4 by mass and has a density of 1.80 g mL-1. Volume of acid required to make one litre of 0.1 M H2S04 solution is :

A 11.10 mL

B 16.65 mL

C 22.20 mL

D 5.55 mL

View Answer

Answer: 5.55 mL

17 An organic compound contains carbon, hydrogen, and oxygen. Its elemental analysis gave C, 38.7% and H, 9.67%. The empirical formula of the compound would be

A CH3O

B CH2O

C CHO

D CH4O

View Answer