Class 11 Basic Concepts of Chemistry MCQs

Here we givens some Class 11 Basic Concepts of Chemistry MCQs, Assertion & Reason question from Class 11, NCERT chemistry chapter-1

1. What will be the molarity of a solution, which contains 5.85 g of NaCl(s) per 500 mL?

(i) 4 mol L^–1

(ii) 20 mol L^–1

(iii) 0.2 mol L^–1

(iv) 2 mol L^–1

2. If 500 mL of a 5M solution is diluted to 1500 mL, what will be the molarity of the solution obtained?

(i) 1.5 M

(ii) 1.66 M

(iii) 0.017 M

(iv) 1.59 M

3. The number of atoms present in one mole of an element is equal to Avogadro number. Which of the following element contains the greatest number of atoms?

(i) 4g He

(ii) 46g Na

(iii) 0.40g Ca

(iv) 12g He

4. If the concentration of glucose (C₆H₁₂O₆) in blood is 0.9 g L^–1, what will be the molarity of glucose in blood?

(i) 5 M

(ii) 50 M

(iii) 0.005 M

(iv) 0.5 M

5. What will be the molality of the solution containing 18.25 g of HCl gas in 500 g of water?

(i) 0.1 m

(ii) 1 M

(iii) 0.5 m

(iv) 1 m

6. One mole of any substance contains 6.022 × 10²³atoms/molecules. Number of molecules of H₂SO₄ present in 100 mL of 0.02M H₂SO₄ solution is

(i) 12.044 × 10²⁰ molecules

(ii) 6.022 × 10²³ molecules

(iii) 1 × 10²³ molecules

(iv) 12.044 × 10²⁰ molecules

7. What is the mass percent of carbon in carbon dioxide?

(i) 0.034%

(ii) 27.27%

(iii) 3.4%

(iv) 28.7%

8. The empirical formula and molecular mass of a compound are CH₂O and 180 g respectively. What will be the molecular formula of the compound?

(i) C₉H₁₈O₉

(ii) CH₂O

(iii) C₆H₁₂O₆

(iv) C₂H₄O₂

9. If the density of a solution is 3.12 g/mL , the mass of 1.5 mL solution in significant figures is.

(i) 4.7g

(ii) 4680 × 10^-3 g

(iii) 4.680g

(iv) 46.80g

10. Which of the following statements about a compound is incorrect?

(i) A molecule of a compound has atoms of different elements.

(ii) A compound cannot be separated into its constituent elements by physical methods of separation.

(iii) A compound retains the physical properties of its constituent elements.

(iv) The ratio of atoms of different elements in a compound is fixed.

11. Which of the following statements is correct about the reaction given below:
    4Fe(s) + 3O₂(g) → 2Fe₂O₃(g)

(i) Total mass of iron and oxygen in reactants = total mass of iron and oxygen in product therefore it follows law of conservation of mass.

(ii) Total mass of reactants = total mass of product; therefore, law of multiple proportions is followed.

(iii) Amount of Fe 2 O 3 can be increased by taking any one of the reactants (iron or oxygen) in excess.

(iv) Amount of Fe 2 O 3 produced will decrease if the amount of any one of the reactants (iron or oxygen) is taken in excess.

12. Which of the following reactions is not correct according to the law of conservation of mass?

(i) 2Mg(s) + O₂(g) → 2MgO(s)

(ii) C₃H₈(g) + O₂(g) → CO₂(g) + H₂O(g)

(iii) P₄(s) + 5O₂(g) → P₄O₁₀(s)

(iv) CH₄(g) + 2O₂(g) → CO₂(g) + 2H₂O (g)

13. Which of the following statements indicates that law of multiple proportion is being followed?

(i) Sample of carbon dioxide taken from any source will always have carbon and oxygen in the ratio 1:2.

(ii) Carbon forms two oxides namely CO₂ and CO, where masses of oxygen which combine with fixed mass of carbon are in the simple ratio 2:1.

(iii) When magnesium burns in oxygen, the amount of magnesium taken for the reaction is equal to the amount of magnesium in magnesium oxide formed.

(iv) At constant temperature and pressure 200 mL of hydrogen will combine with 100 mL oxygen to produce 200 mL of water vapour.

Class 11 Basic Concepts of Chemistry MCQs: Multi Answers

In the following questions two or more options may be correct.

14.One mole of oxygen gas at STP is equal to _______.

(i) 6.022 × 10²³ molecules of oxygen

(ii) 6.022 × 10²³ atoms of oxygen

(iii) 16 g of oxygen

(iv) 32 g of oxygen

15. Sulphuric acid reacts with sodium hydroxide as follows :
H₂SO₄ + 2NaOH ⎯→ Na₂SO₄ + 2H₂O
When 1L of 0.1M sulphuric acid solution is allowed to react with 1L of 0.1M sodium hydroxide solution, the amount of sodium sulphate formed and its molarity in the solution obtained is

(i) 0.1 mol L^-1

(ii) 7.10 g

(iii) 0.025 mol L^-1

(iv) 3.55 g

16.Which of the following pairs have the same number of atoms?

(i) 16 g of O₂ (g) and 4 g of H₂(g)

(ii) 16 g of O₂ and 44 g of CO₂

(iii) 28 g of N₂ and 32 g of O₂

(iv) 12 g of C(s) and 23 g of Na(s)

17.Which of the following solutions have the same concentration?

(i) 20 g of NaOH in 200 mL of solution

(ii) 0.5 mol of KCl in 200 mL of solution

(iii) 40 g of NaOH in 100 mL of solution

(iv) 20 g of KOH in 200 mL of solution

18.  16 g of oxygen has same number of molecules as in

(i) 16 g of CO

(ii) 28 g of N₂

(iii) 14 g of N₂

(iv) 1.0 g of H₂

19. Which of the following terms are unitless?

(i) Molality

(ii) Molarity

(iii) Mole fraction

(iv) Mass percent

20. One of the statements of Dalton’s atomic theory is given below:
“Compounds are formed when atoms of different elements combine in a fixed ratio”
Which of the following laws is  related to this statement?

(i) Law of conservation of mass

(ii) Law of definite proportions

(iii) Law of multiple proportions

(iv) Avogadro law

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Basic Concepts of Chemistry Assertion & Reason Questions

(a)Assertion and reason both are correct statement and reason is correct

explanation for assertion.

(b) Assertion and reason both are correct statement and reason is not correct

explanation for assertion.

(c)Assertion is correct statement but reason is wrong statement.

(d) Both assertion and reason are incorrect.

1. Assertion:22 carat gold is a mixture.

Reason    :A compound has fixed composition of the elements present in it.

2. Assertion: The standard unit of expressing mass of atom is called u.

Reason    : u represents unit mass.

3. Assertion: Empirical and molecular formulae of NaHCO₃ are the same.

Reason    : Upon heating, NaHCO₃ evolves CO₂ gas.

4. Assertion: Both 32 g of SO₂ and 8 g of CH₄ have same number of molecules.

Reason    : Equal moles of substances have equal number of molecules.

5. Assertion: Atomic mass of Calcium is 40 u.

Reason    : An atom of Ca is 40 times heavier   than an atom of carbon with mass 12 u.

6. Assertion : Components of a homogeneous mixture cannot be separated by using physical

methods.

Reason    : Components of a homogeneous mixture is uniform throughout as the components

react to form a single compound.

7. Assertion :1 mole of N and 1 mol of N₂ contain equal number of particles.

Reason    : 1 mole of particles is always double than 1 mole of atoms in all the diatomic molecules.

8. Assertion : Molarity of a solution does not depend upon temperature where as molality depends.

Reason     : Molarity and Molality both depend only upon the number of moles of solute particles.

9. Assertion : 12 parts by mass of carbon in CO and CO₂ molecules combine with 16 and 32 parts by

mass of O respectively.

Reason    :A given compound always consists of the same elements combined in a fixed proportion

by mass.

10.Assertion : One mole of NaCl contains 6.022 x 10²³ formula units of NaCl.

Reason     : 58.5 g of NaCl also contains 6.022 x 10²³ formula units of NaCl.

Also Read: CBSE Class 12 Electrochemistry MCQs