REDOX REACTIONS AND ELECTROCHEMISTRY – 3

1) The pH of N/100 H2SO4 solution is
a) 1
b) 2
c) 3
d) 4

2) The pH of N/10 NaOH is
a) 11
b) 13
c) 10
d) 8

3) @ The pH of 0.5 M KOH is
a) 13.699
b) 11.0
c) 11.699
d) 12.699

4) The pH of a solution of HCl is 4. The molarity of the solution is
a) 4.0
b) 0.4
c) 0.0001
d) 0.04

5) 0.1 N solution of a weak base has a pH = 9. What is the percentage ionisation of the base ?
a) 01.%
b) 0.01%
c) 0.2%
d) 0.02%

6) The pH of a solution is 4. The H+ ion concentration of the solution is
a) moles/litre
b) 4 moles/litre
c) moles/litre
d) 0.4 moles/litre

7) The pH of a solution at 25°C is 2. If the pH is to be doubled then the hydronium ion concentration of the solution should be
a) Halved
b) Doubled
c) Increased by 100 times
d) Decreased by 100 times

8) A solution of pH 9 is one thousand times as basic as a solution of pH… ?
a) 6
b) 7
c) 8
d) 10

9) The pH of a solution is 4. What should be the change in H+ ion concentration of the solution if the pH is to be increased to 5?
a) Halved
b) Doubled
c) Decreased by 10 times
d) Decreased to half of its original value

10) If 900 ml of more distilled water is
added to 100 ml of aqueous HCl of pH = 1.0, the pH of the resulting solution will become

a) 1.0
b) 2.0
c) 4.0
d) 7.0

11) At 80°C, the H3O+ ion concentration in pure water is 10-6. What is the value of the ionic product at 80°C in moles2litre-2 ?
a)
b)
c)
d)

12) If the [OH] ion concentration is 1 x 10-8 ion/litre, its pH is
a) 6
b) 7
c) 5
d) 8

13) The value of dissociation constants of some acids are given below. Indicate which is the strongest acid in water .
a)
b)
c)
d)

14) The value of pKw at 25°C is
a) + 7
b) – 14
c) + 14
d)

15) Which of the following when added to 35 ml of 0.1 M KOH, would cause the largest change in pH ?
a) 2.5 ml of 1.0 M HCl
b) 25 ml of 0.2 M HCl
c) 25 ml of 0.05 M HCl
d) 25 ml of distilled water

16) The pH of boiling water (373 K) is : Given Kw=10-12 (at 373 K)
a) 12
b) 8
c) 6
d) 2

17) At 90°C pure water has [H3O+] = 10-6 mole litre-1. What is the value of Kw at 90°C ?
a)
b)
c)
d)

18) @ The ionisation constant of water at 37°C is 2.42 x 10-14 mole2 litre-2. What is the pH for a neutral solution at this temperature?
a) 0
b) 7.2
c) 7.0
d) 6.82

19) What is the pH of a neutral solution at 50°C. ( pKw = 13.2 at 50°C ?)
a) 6.0
b) 6.63
c) 7.13
d) 7.0

20) The pH of a solution is 5.0. To this solution sufficient acid is added to decrease the pH to 2.0. The increase in concentration of H+ ions is
a) 1000 times
b) 5/2 times
c) 100 times
d) 5 times

21) 0.4 g of NaOH present in one litre solution shows the pH
a) 12
b) 2
c) 6
d) 10

22) @

A certain buffer solution contains equal concentrations of X and HX. The Kb for X is 10-10. The pH of the buffer is
a) 4
b) 7
c) 14
d) 10

23) The pH of a 10-10 M HCl solution is approximately
a) 10
b) 7
c) 1
d) 14

24) 10-6 M HCl is diluted to 100 times. Its pH is
a) 6.0
b) 8.0
c) 6.95
d) 9.5

25) @ The pH of 10-10 M NaOH solution is nearest to
a) 10
b) 7
c) 4
d) –10

26) 10-6 M NaOH is diluted 100 times. The pH of the diluted base is
a) Between 6 and 7
b) Between 10 and 11
c) Between 7 and 8
d) Between 5 and 6

27) The pH of a 10 M solution of HCl is
a) Less than zero
b) Zero
c) 2
d) 1

28) Which buffer solution will have a pH>7 ?
a)
b) HCOOH+HCOONa
c)
d)

29) Any buffer can be used as a buffer upto
a) 10 pH units
b) 5 pH units
c) 2 pH units
d) 1 pH unit

30) The pH of 10-8 M NaOH is
a) 8.0
b) 6.96
c) 12.0
d) 7.04

31) The pH of a solution is 5.96. If H+ ion concentration decreases by 100 times, then the nature of the solution is
a) Acidic
b) Basic
c) Neutral
d) Amphoteric

32) The pH value of a 10-5 M aqueous solution of NaOH is
a) 5
b) 7
c) 9
d) 11

33) The pH of H2SO4 = 2. Its molar concentration is
a) 0.01
b) 0.005
c) 0.02
d) 0.05

34) The pH of a 0.005 M aqueous solution of sulphuric acid is
a) 0.005
b) 2
c) 1
d) 0.01

35) Assuming complete dissociation, the pH of a 0.01 N NaOH solution is
a) 2.0
b) 14.0
c) 12.0
d) 0.01

36) @ The pH of a solution is 4.0 at 25°C. Its pOH would be (Kw=10-14).
a) 4.0
b) 10.0
c) 8.0
d) 6.0

37) 50 ml of 2N CH3COOH mixed with 10 ml of IN sodium acetate solution will have an approx. pH of (Ka= 10-5)
a) 4
b) 5
c) 6
d) 7

38) When 1.0 ml of dilute HCl is added to 100 ml of a buffer solution of pH = 4, the pH of the solution becomes
a) 7
b) 2
c) 10
d) Does not change

39) If the H+ ion concentration of a given solution is 5.5 x 10-3 M, the pH of the solution is
a) 2.26
b) 3.40
c) 3.75
d) 47.6

40) The pH of a solution containing 10 ml of 0.1 N NaOH and 10 ml of 0.05 N H2SO4 would be
a) 0
b) 1
c) 7
d) > 7

41) How many times more acidic is a solution of pH = 2 than a solution of pH = 6 ?
a) 10000
b) 12
c) 400
d) 4

42) A 0.2 M solution of HCOOH is 3.2% ionised. Its ionisation constant is
a)
b)
c)
d)

43) An aqueous solution of 0.1 M NH4Cl will have a pH close to
a) 9.1
b) 8.1
c) 7.1
d) 5.1

44) @ Which solution will have a pH closest to 1.0 ?
a) 100 ml of M/10 HCl + 100 ml of M/10 NaOH
b) 55 ml of M/10 HCl + 45 ml of M/10 NaOH
c) 10 ml of M/10 HCl + 90 ml of M/10 NaOH
d) 75 ml of M/5 HCl + 25 ml of M/5 NaOH

45) The H+ ion concentration in 0.001 M CH3COOH (Ka= 1.8x 10-5) is 1.34x 10 4g
ion/litre. The H+ ion concentration if 0.164 g. of CH3COONa is added to a litre of 0.001 M CH3COOH will be

a)
b)
c)
d)

46) The [H3O+] in rain water of pH 4.35 is
a)
b)
c)
d)

47) The pH of 0.1 M HCl is approx. 1.0. The approximate pH of 0.05 M H2SO4 is
a) 0.05
b) 0.5
c) 1
d) 2

48) Ka for HCN is 5 x 10-10 at 25°C. To maintain a constant pH = 9, the volume of 5M KCN solution required to be added to 10 ml of 2M HCN solution is
a) 4 mL
b) 7.95 mL
c) 2 mL
d) 9.3 mL

49) A 0.01 M ammonia solution is 5% ionised. The concentration of OH ions is
a) 0.005 M
b) 0.0001 M
c) 0.0005 M
d) 0.05 M

50) The pH of a 0.02 M HCl solution is
a) 2
b) 1.7
c) 0.3
d) 2.2

51) The pH of a 0.01 M solution of CH3COOH having 12.5% degree of dissociation is
a) 4.509
b) 3.723
c) 2.903
d) 5.623

52) The possible H+ ion concentration for an acidic solution is
a)
b)
c)
d)

53) @ The pH of the solution produced when an aqueous solution of strong acid of pH = 5 is mixed with an equal volume of an aqueous solution of strong acid of pH = 3 is
a) 3.3
b) 3.5
c) 4.5
d) 4.0

54) The pKa of an acid whose ionisation constant is 1 x 10-3 is
a) 3
b) – 3
c) -9
d) + 9

55) A buffer mixture of CH3COOH and CH3COOK has pH = 5.24. The ratio of
CH3COO/CH3COOH in this buffer is (pKa =4.74).

a) 3 : 1
b) 1 : 3
c) 1 : 1
d) 1 :2

56) The weight of HCl present in one litre of solution, if the pH of the solution is 1, is
a) 3.65 g
b) 36.5 g
c) 0.365 g
d) 0.0365 g

57)

The pH of a solution formed by mixing 40 ml of 0.10 M HC1 and 10 ml of 0.45 M NaOH is.
a) 5
b) 8
c) 12
d) 10

58) 20 ml of 0.1 NHC1 is mixed with 20 ml of a 0.1 N KOH solution. The pH of the solution would be
a) 0
b) 7
c) 2
d) 9

59) The number of moles of [OH] ion in 0.3 litre of 0.0005 molar solution of Ba(OH)2 is
a) 0.0075
b) 0.0015
c) 0.0030
d) 0.0050

60) The pH of 0.05 M Mg(OH)2 is
a) 13
b) 10
c) 1
d) 0

61) pH of M/200 Ba(OH)2 solution (assuming complete dissociation) is
a) 2
b) 12
c) 12.70
d) 11.6

62) 0.04 g of pure NaOH is dissolved in 10 litres of distilled water. The pH of the solution is
a) 9
b) 10
c) 11
d) 12

63) The dissociation constant of an acid HA is 1 x 10-5. The pH of a 0.1 M solution of the acid HA will be approximately
a) 3
b) 5
c) 1
d) 6

64) 10 ml of a solution contains 0.1 M NH4C1 + 0.1 M NH4OH. What addition would not change the pH of the solution ?
a) Adding 1 ml water
b)
c)
d)

65) When 10-8 mole of HCl is dissolved in one litre of water, the pH of the solution is
a) 8
b) 7
c) Above 8
d) Below 7

66) An aqueous solution contains a substance which yields 4×10-3 mole litre-1 ion of H3O+. If log 2 = 0.3010, the pH of the solution is
a) 1.5
b) 2.398
c) 3.0
d) 3.4

67) The pH of 1% ionised 0.1 M solution of acetic acid is
a) 1
b) 2
c) 3
d) 11

68) A monoprotic acid is 1.00 M solution and is 0.001% ionised. The dissociation constant of the acid is
a)
b)
c)
d)

69) The pH of a 1 x 10-8 M aqueous solution of HCl is slightly less than 7 because
a) The ionisation of HCl is incomplete
b) The ionisation of water negligible
c) The ionisation of water at such a low concentration of HCl is significant
d)

70) @ One mole of water contains 10-7 moles of H+ ions. The degree of ionisation of water is
a)
b)
c)
d)

71) @ The pH of a solution whose [H+] is one mole per litre is
a) 1.0
b) 0.1
c) 0
d) 1.5

72) HClO is a weak acid. The [H+] in 0.1 M solution of HClO (Ka = 5x 10-8) will be equal to
a)
b)
c)
d)

73) Which of the following will occur if a 0.1 M solution of a weak acid is diluted to 0.01 M at constant temperature ?
a)
b) The pH will decrease
c) The percentage of ionisation increases
d) The activation constant will increase

74) Which would decrease the pH of 25 cm3 of a 0.01 M HCl solution?
a) The addition of Mg
b)
c)
d) None

75) @ The pH of 1 M CH3COONa solution is: (Ka=1.810-5, Kw = 10-14 mole2 litre2-)
a) 2.4
b) 3.6
c) 4.8
d) 9.4

76) @

How many H+ ions are contained in 1 ml of a solution whose pH = 13 ?
a)
b)
c)
d)

77) What is the value of [H+][OH] in a 1 M solution of NaOH?
a)
b)
c) 10
d)

78) A solution is prepared by mixing 500 ml of 0.2 M CH3COOH and 500 mL of 0.4 M CH3COONa. What is the H+ ion concentration of the solution, if Ka for CH3COOH is 1.8×10-5 ?
a)
b)
c)
d)

79) What is the pH of 10-3 M ammonium cyanide solution, if KHCN = 7.2 x 10-11 and KNH3 = l.8×10-5 ?
a) 14
b) 9.7
c) 12.0
d) 7.5

80) 20 ml of HCl is completely neutralised with 40 mL of 0.05 M NaOH. The pH of the original HCl solution is
a) 3
b) 2
c) 1
d) 1.5

81) The concentration of acetic acid required to give 3.5 x 10-4 moles/litre of H+ ions is : (Given Ka= 1.8 x 10-5)
a)
b) 6.8
c) 1.94
d) 19.4

82) @ 100 ml of 0.1 M H2SO4 is diluted to 250 ml. What is the increase in pH ?
a) 0.3979
b) 0.6990
c) 1.0969
d) None

83) Calculate the pH of a solution obtained by mixing 50 ml of N HCl and 30 ml of N NaOH.
a) 0.6021
b) 0.2106
c) 0.2602
d) None

84) The pH of a solution containing 40 g of NaOH in 500 ml water is
a)
b) 13.3010
c) 12
d) 12.3010

85) What is the ratio of [Salt]/[Acid] for a buffer solution of pH = 4.70, given that Ka=1.75 x 10-5 ?
a) 0.8772
b) 0.7872
c) 0.2778
d) None

86) @ What is the pH of a buffer solution containing 0.015M NH4OH and 0.025M NH4Cl? The Kb of NH4OH = 1.5 x 10-5 and Kw= 1 x 10-14 .
a) 9.0335
b) 8.5
c) 7.0
d) 12.0

87) What is the pH of a buffer solution containing 12 g CH3COOH and 16.4 g. of CH3COONa in 500 ml of solution. Ka for CH3COOH =1.8 x 10-5 ?
a) 4.7447
b) 4.4774
c) 4.4477
d) None

88) @ The pH of 0.4833 % solution of HCl is
a) 0.8239
b) 0.2389
c) 0.9328
d) None

89) What is the amount of acetic acid that must be dissolved in 100 mL of solution to get a pH = 2.4? The Ka for CH3COOH = 1.85 x 10-5 and the mol. wt of CH3COOH = 60 ?
a)
b)
c)
d)

90) What is the pH of 0.001 M solution of Ba(OH)2 assuming complete ionisation ?
a) 11.3
b) 12.4
c) 13.1
d) 10.5

91) A solution of HCl has a pH = 5. If one ml of it is diluted to one litre, what will be the pH of the resulting solution ?
a) 6.9788
b) 7.0
c) 7.9788
d) None

92) What volume of 0.1 M sodium formate solution should be added to 50 ml of 0.05 M formic acid to produce a buffer solution of pH = 4. Given pKa = 3.80 ?
a) 39.62 ml
b) 62.39 ml
c) 93.26 ml
d) None

93) To prepare a buffer solution of pH = 6, by mixing CH3COONa and CH3COOH, the ratio of the concentration of salt and acid should be (Ka=10-5).
a) 1:10
b) 10:1
c) 100 : 1
d) 1 : 100

94) The pH of a mixture of CH3COOH + CH3COONa after adding water shows a …… … value
a) Decreased
b) Increased
c) Constant
d) None

95) The pH of a 0.4 M HNO3 solution is
a) 2
b) 3
c) 0.398
d) 4

96) At 25 °C, the dissociation constants of CH3COOH and the weak base BOH in aqueous solution are almost the same. The pH of a solution of 0.01 N CH3COOH is 4.0 at 25°C. The pH of 0.1 N BOH solution at the same temperature would be
a) 4
b) 3
c) 10
d) 12

97) The concentration of [H+] and the concentration of [OH] of a 0.1M aqueous solution of a 2% ionised weak acid is
a)
b)
c)
d)

98) The pH value of HCl and NaOH solution each of N/100 strength will be respectively
a) 2 and 2
b) 2 and 12
c) 12 and 2
d) 2 and 10

99) @ 50 ml of water is added to 50 ml solution of Ba(OH)2 of strength 0.01M. The pH value of the resulting solution will be
a) 8
b) 10
c) 12
d) 6

100) @ The dissociation constant of a weak monobasic acid Ka = 1 x 10-5. The pH of 0.1M solution of that acid would be
a) 5
b) 1
c) 2
d) 3


Answer :

 

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