CHEMISTRY IS NO MORE A MYSTERY WITH DILSHAD SIR

CHAPTER PRACTICE PROBLEMS

Mole concept and Balancing of Redox Reaction

1. At 627°C when calcium carbonate is heated at 1 atm pressure, produced carbon dioxide occupies
224 ml at STP. Amount of calcium carbonate heated was
(a) 0.01 gm (b) 1 gm (c) 0.033 gm (d) 0.33 gm

2. If 150 ml of 0.03M ammonium sulfate solution is added to 300 ml of water then molarity of
ammonium ion would become
(a) 0.01 (b) 0.03 (c) 0.02 (d) 0.06

3. To make a solution of strength 0.15 (M) with respect to NO3– ion in which ratio are solutions of
M M
 PbNO3 2 and  KNO3 to be mixed?
 10   10 
(a) 1 : 2 (b) 1 : 1 (c) 2 : 1 (d) 1 : 3

4. If atomic weight of sodium is 23 a.m.u. then weight of one atom of sodium is

(a) 23 gm (b) 3.82 1023 g (c) 1.66031024 g (d) None of these

5. In our chemical laboratory atmosphere the density of water is 0.98 g cm–3. The molar volume of
water is
(a) 22.4 dm3 (b) 18 dm3 (c) 18 cm3 (d) 18.37 cm3

6. 1
 wt. of one atom of C12 isotope is called
12
(a) 1 a.m.u. (b) atomic weight (c) molecular weight (d) gram atomic weight

7. Increase in oxidation number of an atom in a molecule is called

(a) oxidation process (b) reduction process
(c) redox process (d) disproportionation process

8. Oxidation number of an atom or a group is

(a) an integer (b) a fraction
(c) positive or negative one (d) all the above are possible

9. Oxidation number of oxygen in KO2 is

1
(a) –1 (b) –2 (c) +1 (d) –
2
10. Oxidation number of the atom underlined the particular atom in the following molecule CH3CHO
(a) –1 (b) 3 (c) +1 (d) –3

11. If 18 gram of glucose is dissolved in 18 ml of water, then molality of the produced solution
(density of water being 1 gm cm–3) would be
(a) 1 (b) 5.555 (c) 0.555 (d) 1.8

12. In a closed vessel 12.5 gm of nitrogen is taken with 2.8 gm of hydrogen and heated in presence of
catalyst to produce ammonia. The limiting reagent of this system is
(a) nitrogen (b) hydrogen (c) ammonia (d) none of these

13. When 16 gm of oxygen reacts with 31 g of nitric oxide then the weight of produced nitrogen
dioxide would be
(a) 47.53 gm (b) 47 gm (c) 46 gm (d) none of these

14. The mass of N 2 F4 produced by the reaction of 2.0 g of NH 3 and 8.0 g of F2 is 3.56 g. What is the
per cent yield ?
2 NH 3  5F2  N 2 F4  6 HF
(a) 79.0 (b) 71.2 (c) 84.6 (d) None of these
RD
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15. What is the oxidation number of phosphorous in H3PO2
(a) +7 (b) –1 (c) +2 (d) +1

16. The change in oxidation number of iron, when steam is passed through a red hot iron rod:
3Fe + 4H2O  Fe3O4 is
(a) +2 (b) +3 (c) +2 & +3 (d) +8/3

17. The percentage by volume of C 3 H 8 in a gaseous mixture of C 3 H 8 , CH 4 and CO is 20. When 100
mL of the mixture is burnt in excess of O2 , the volume of CO 2 produced is:
(a) 90 mL (b) 160 mL (c) 140 mL (d) None of these

18. Which pair of the following is having oxidizing as well as reducing property?
(a) (SO2 & H2O2) (b) (CO2 & MnO2) (c) (Na2SO3 & Fe2O3) (d) (H2S & Hg2Cl2)

19. In alkaline medium permanganate (MnO4–) ion is converted to manganesedioxide (MnO2). In the
balanced chemical equation for the above reaction how many mole of electrons would be utilized?
(a) 5 (b) 6 (c) 1 (d) 3

20. Number of atoms in 9 gm of water is

(a) 3.0115 × 1023 (b) 0.5 × 1023 (c) 6.023 × 1023 (d) 9.0345 × 1023

21. 6.02 × 1020 molecules of substance weigh 44 mg. The molar mass of the substance is
(a) 44 (b) 22 (c) 4.4 (d) 44.5

22. The number of gram of hydrogenchloride required to prepare 400 ml of 5M HCl in water is
(a) 36.5 (b) 73 (c) 7.3 (d) 3.65

23. An oxide of nitrogen with molecular mass 92 has 30.4% nitrogen. The molecular formula is
(a) NO2 (b) N2O3 (c) N2O4 (d) N2O5

24. What quantity of ammonium sulphate is necessary for the production of NH3 gas sufficient to
neutralize a solution containing 292 g of HCl?
[HCl = 36.5; (NH4)2SO4 = 132, NH3 = 17]
(a) 272 g (b) 403 g (c) 528 g (d) 1056 g
25 In reaction, 4NH3(g) + 5O2(g)  4NO(g) + 6H2O(g) when 1 mole of ammonia and 1 mole of O2
are made to react to completion,
(a) 1.0 mole of H 2 O will be produced (b) 1.0 mole of NO will be produced
(c) all the oxygen will be consumed (d) all the ammonia will be consumed.

26. The simplest formula of a compound containing 50% of element X (at mass 10) and 50% of
element Y (at mass 20) is
(a) XY (b) X2Y (c) XY3 (d) X2Y3

27. What will be the volume of CO2 at NTP obtained on heating 10 gms of (90% pure) lime stone.
(a) 22.4 L (b) 2.016 L (c) 2.24 L (d) 20.16 L
28. Irrespective of the source, pure sample of water always yields 88.89% mass of oxygen and 11.11%
mass of hydrogen. This is explained by the law of
(a) conservation of mass (b) constant proportion
(c) multiple proportion (d) constant volume.

29. Amongst the following identify the species with an atom in +6 oxidation state.
(a) K3[Cr(CN)6] (b) NiF62– (c) MnO4– (d) CrO2Cl2

30. How many gram of KCl would have to be dissolved in 60 g of H2O to give 25% by weight of
solution?
(a) 15 g (b) 1.5 g (c) 11.5 g (d) 31.5 g

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31. What volume of CCl4 having density 1.5 g/c.c. contains 1 × 1025 chlorine atoms.
(a) 1704 litre (b) 426 ml. (c) 42.6 ml. (d) 213 ml.

32. When 10g of propane is made to react with 4 g of oxygen then weight of CO2 produced will be
(a) 9.98 g (b) 3.3 g (c) 4.4 g (d) 5.5 g

33. Calculate the molarity of 20% solution of KOH by mass whose density is 1.02 gml–1.
(a) 18.2 (b) 36.4 (c) 1.82 (d) 3.64

34. 1.12 ml of a gas is produced at STP by the action of 4.12 mg of alcohol, ROH with methyl
magnesium iodide. The molecular mass of alcohol is
(a) 16.0 (b) 41.2 (c) 82.4 (d) 156.0

35. Oxidation number of oxygen in O2F2 is

(a) –2 (b) +2 (c) –1 (d) +1

36. BaO2 is an example of

(a) peroxide (b) super oxide (c) dioxide (d) suboxide.

37. 3HNO2  HNO3 + 2NO + H2O is an example of

(a) comproportionation reaction (b) oxidation process
(c) reduction process (d) disproportionation reaction

38. The number of moles of water required in balancing the following chemical equation when
corresponding reaction takes place in acid medium.
N2O4 + BrO3–  NO3– + Br–
(a) 6 (b) 3 (c) 4 (d) 5

39. The number of moles of electron to be added in the reduction process of the balanced chemical
equation for the following reaction:
Cu + NO3– + H+  Cu2+ + NO + H2O
(a) 6 (b) 3 (c) 2 (d) 4

40. Oxidation number of iodine in ICl is

(a) –1 (b) +1 (c) 0 (d) +3

41. In FeC2O4 carbon, in chemical reactions, can

(a) decrease its O.N. (b) not change its O.N. (c) increase its O.N. (d) Both (b) & (c).

42. Oxidation number of sulphur in Marshal acid (H2S2O8) is

(a) +8 (b) –6 (c) +4 (d) +6

43. Sulphurdioxide can act as oxidizing as well as reducing agent because oxidation number of sulphur
in SO2
(a) can increase only
(b) can decrease only
(c) can increase as well as decrease depending on the situation
(d) can neither increase nor decrease.

44. If 1 mole of ethanol (C2H5OH) completely turns to CO2 and H2O, the weight of CO2 produced will
be
(a) 22.0 g (b) 45.0 g (c) 66.0 g (d) 88.0 g

45. In the following reaction starting with the reactants only:

N2H4 + Cu(OH)2  N2 + Cu + H2O
If 3.175 g of copper is produced, then at S.T.P. volume of nitrogen would be collected from it is.
(a) 1120 mL (b) 560 mL (c) 11200 mL (d) 56 mL
In balanced redox reaction of Cr2O72– with C2O42– in acidic medium how many moles of CO2

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46. would be produced if Cr3+, CO2 & H2O are the only products in this reaction.
(a) 2 (b) 7 (c) 4 (d) 6

1
47. The example of oxidation number  of nitrogen is
3
(a) N3H (b) NH3 (c) NCl3 (d) N2O3

48. A complex of iron contains 45.6% iron by mass. Find out number of iron atoms in 5.00 gm of this
complex.
(a) 2.45 × 1023 (b) 2.28 × 1022 (c) 2.45 × 1022 (d) 2.45 × 1023

49. The mass of 1 × 1023 molecules of methane is

(a) 16 gm (b) 1 × 1023 gm (c) 2.657 g (d) 1 × 1023 Kg

50. If 2800 mL of a sulphur vapour at S.T.P. it weighs 32 g, atomic weight of sulphur being 32,
molecular formulas of sulphur in that vapourized state is
(a) S (b) S4 (c) S3 (d) S8

Answer Keys:

1 B 2 C 3 B 4 B 5 D
6 A 7 A 8 D 9 D 10 A
11 B 12 A 13 C 14 D 15 D
16 D 17 C 18 A 19 D 20 D
21 A 22 B 23 C 24 C 25 C
26 B 27 B 28 B 29 D 30 A
31 B 32 B 33 D 34 C 35 D
36 A 37 D 38 B 39 A 40 B
41 C 42 D 43 C 44 D 45 B
46 D 47 A 48 C 49 C 50 D

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