Class 11 Chemistry Mole Concept MCQs JEE/NEET

Mole Concept JEE/NEET

Multiple Choice Questions with One Correct Answer

1. Which of the following is not a mixture?

(a) Gasoline (b) Distilled alcohol

2. If 6.3 g of NaHCO₃ is added to 15.0 g CH₃COOH solution, the residue is found to weigh 18.0 g. What is the mass of CO₂ released in the reaction?

(a) 4.5 g (b) 3.3 g

3. 0.003924 have . . . . . significant figures.

(a) 6 (b) 4

4. The solid-like conducting state of gases with free electrons is called

(a) sol state (b) gel state

5. The mass of nitrogen per gram hydrogen in the compound hydrazine is exactly one and a half times the mass of nitrogen in the compound ammonia. This fact illustrates the

(a) law of conservation of mass

(b) multiple valencies of nitrogen

(d) law of definite proportions

6. The answer to the calculation

significant figures will be

(a) 3.579 (b) 3.570

7. Carbon dioxide contains 27.27% of carbon, carbon disulphide contains 15.79% of carbon and sulphur dioxide contains 50% of sulphur. This data is an agreement with

(a) law of conservation of mass

(b) law of definite proportions

(d) law of reciprocal proportions

8. Unit J Pa^–1 is equivalent to

(a) m³ (b) cm³

(d) dm³ (d) None of these

9. In multiplication and division, the significant figures of the answer must be the same as that in the quantity with ………….. a number of significant figures.

(a) maximum (b) 3

10. One part of element A combines with two parts of another element B. 6 parts of element C combines with 4 parts of B. If A and C combine together, the ratio of their weights will be governed by

(a) law of definite proportions

(b) law of multiple proportions

(d) law of conservation of mass

11. The matter is anything which occupies . . . A . . . and has . . . B . . . Here A and B are.

(a) density and mass (b) volume and mass

12. How many significant figures are there in (respectively)(1) 73.000 g (2) 0.0503 g and (3) 2.001 s?

(a) 3, 3, 4 (b) 3, 4, 5

13. An example of a homogeneous mixture is

(a) a mixture of soil and water

(b) a mixture of salt and sand grains

(d) None of the above

14. The number of significant figures in Avogadro’snumber is

(a) four (b) two

15. n-gram of a substance X-reacts with m gram of substance Y to from p gram of substance R and q gram of substance S. This reaction can be represented as follows

X + Y = R + S

The relation which can be established in the amounts of the reactants and the products will be

(a) n – m = p – q (b) n + m = p + q

16. One atom of an element X-weight 6.643 × 10^–23 g. Number of moles of atoms in 20 kg is

(a) 140 (b) 150

17. A sample of ammonium phosphate (NH₄)₃PO₄ contains 6.36 moles of hydrogen atoms. The number of moles of oxygen atoms in the sample is (atomic mass of N = 14.04, H = 1, P = 31, O = 16)

(a) 0.265 (b) 0.795 (c) 2.12 (d) 4.14

18. The sample with the largest number of atoms is

(a) 1 g of O₂(g) (b) 1 g of Ni(s)

19. If H₂SO₄ ionises as H₂SO₄ + 2H₂O → 2H₃O⁺ + SO₂^–4, then total number of ions produced by 0.1 MH₂SO₄ will be

(a) 9.03 × 10²¹ (b) 3.01 × 10²²

20. The number of sodium atoms in 2 moles of sodium ferrocyanide is

(a) 12 × 10²³ (b) 26 × 10²³

21. The molecular weight of air will be (N₂—78%, O₂—21%, Ar—0.9% and CO₂—0.1%)

(a) 18.64 (b) 24.968

22. Out of 1.0 g dioxygen, 1.0g (atomic) oxygen and 1.0 g ozone, the maximum number of molecules are contained in

(a) 1.0 g of atomic oxygen

(b) 1.0 g of ozone

(d) All contain same number of atoms

23. A sample of AlF₃ contains 3.0 × 10²⁴ F ions. The number of formula units in this sample is

(a) 9.0 × 10²⁴ (b) 3.0 × 10²⁴

24. How many of Al₂(SO₄)₃ would be in 50 g of the substance? [UP SEE 2005]

(a) 0.083 mol (b) 0.952 mol

25. If 0.5 moles of BaCl₂ is mixed with 0.2 mole of Na₃PO₄, the maximum number of moles of Ba₃(PO₄)₂ that can be formed is

(a) 0.7 (b) 0.5

26. Two elements X (at. wt. 75) and Y (at. wt. 16) combine to give a compound having 75.8% of X. The formula of compound will be

(a) XY (b) X₂Y

27. A sample of copper sulphate pentahydrate contains 8.64 g of oxygen. How many grams of Cu is present in this sample?(Atomic mass of Cu = 63.6, S = 32.06, O = 16)

(a) 0.952 g (b) 3.816 g

28. The number of water molecules present in a drop of water (volume 0.0018 mL) at room temperature is

(a) 6.023 × 10¹⁹ (b) 1.084 × 10¹⁸

29. Zinc sulphate contains 22.64% of zinc and 43.9% of water of crystallization. If the law of constant proportions is true then the weight of zinc required to produce 20 g of the crystals will be

(a) 45.3 g (g) 4.53 g

30. Which of the following pairs contains equal number of atoms?

(a) 11.2 cc (STP) of nitrogen and 0.015 g of nitric oxide

(b) 22.4L (STP) of nitrous oxide and 22.4 L of nitric oxide

(d) 1 mole of H₂O₂ and 1 mole of N₂O₄

Answers

1. (b) 2. (b) 3. (b) 4. (c) 5. (c) 6. (d) 7. (d) 8. (a) 9. (d) 10. (c)

11. (c) 12. (d) 13. (c) 14. (a) 15. (b) 16. (d) 17. (c) 18. (c) 19. (d) 20. (d)

21. (c) 22. (a) 23. (d) 24. (d) 25. (d) 26. (d) 27. (b) 28. (a) 29. (b) 30. (a)

EXPLANATIONS

According to the law of conservation of mass,
mass of reactants = mass of products
∴ 6.3 + 15.0 = 18.0 + x
or x = 21.3 – 18.0 = 3.3 g
As the ratio of masses of nitrogen per gram of hydrogen in hydrazine and NH3

i.e, the law of multiple proportions.

Answer in significant figures = 3.6

In CS₂
C: S mass ratio is 15.79: 84.21 15.79 parts of carbon combine with sulphur = 84.21
∴ 27.27 parts of carbon will combine with

Hence, the ratio of S: O is 145.434: 72.73 i.e, 2: 1
In SO2, the ratio of S: O is 1: 1
Since, the ratio of S: O is a simple whole-number ratio, therefore the law of reciprocal proportions is proved.