The pKa of a weak acid (HA) is 4.5. The pOH of an aqueous buffer

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 Multiple Choice QuestionsMultiple Choice Questions

11.

pKa of a weak acid (HA) and pKb of a weak base (BOH) are 3.2 and 3.4, respectively. The pH of their salt (AB) solution is

  • 7.2

  • 6.9

  • 7.0

  • 7.0

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12.

In the following reactions, ZnO is respectively acting as a/an :
(a) ZnO + Na2O → Na2ZnO2
(b) ZnO + CO2 → ZnCO3

  • base and acid

  • base and base

  • acid and acid

  • acid and acid

1312 Views

13.

The equilibrium constants KP1 and KP2 for the reactions X ⇌2Y and Z ⇌ P + Q, respectively are in the ratio of 1 : 9. If the degree of dissociation of X and Z be equal then the ratio of total pressure at these equilibria is

  • 1:1

  • 1:36

  • 1:9

  • 1:9

1196 Views

14.

For the following three reactions a, b and c, equilibrium constants are given

a. CO (g) + H2O (g) ⇌ CO2 (g)+ H2 (g); K1
b. CH4(g) + H2O (g) ⇌ CO (g) + 3H2 (g); K2
c. CH4(g) + 2H2O (g) ⇌ CO2 (g) + 4H2 (g); K2
Which of the following relations is correct?

  • K1√K2 = K3

  • K2K3 = K1

  • K3 = K1K2

  • K3 = K1K2

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15.

Four species are listed below
i. HCO3
ii. H3O+
iii. HSO4
iv. HSO3F
Which one of the following is the correct sequence of their acid strength?

  •  iv < ii < iii < i

  • ii < iii < i < iv

  • i < iii < ii < iv

  • i < iii < ii < iv

442 Views

16.

The pKa of a weak acid, HA, is 4.80. The pKb of a weak base, BOH, is 4.78. The pH of an aqueous solution of the corresponding salt, BA, will be 

  • 9.58

  • 4.79

  • 7.01

  • 7.01

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17.

The pKa of a weak acid (HA) is 4.5. The pOH of an aqueous buffered solution of HA in which 50% of the acid is ionized is

  • 4.5

  • 2.5 

  • 9.5

  • 9.5


C.

9.5

For buffer solution



as HA is 50% ionized so [Salt] = [Acid]
pH = 4.5 pH + pOH = 14
⇒ pOH = 14 – 4.5 = 9.5

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18.

Regular use of which of the following fertilizers increases the acidity of soil ?

  • Potassium nitrate

  • Urea

  • Superphosphate of lime

  • Superphosphate of lime

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19.

An ideal gas is allowed to expand both reversibly and irreversibly in an isolated system. If Ti is the initial temperature and Tf is the final temperature, which of the following statements is correct?

  • (Tf)irrev > (Tf)rev

  • Tf > Ti for reversible process but Tf = Ti for irreversible process

  • (Tf)rev = (Tf)irrev

  • (Tf)rev = (Tf)irrev

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20.

The equilibrium constant for the reaction

SO subscript 3 space left parenthesis straight g space right parenthesis space rightwards harpoon over leftwards harpoon with space space space space space on top space SO subscript 2 space left parenthesis straight g right parenthesis space plus space 1 half space straight O subscript 2 space left parenthesis straight g right parenthesis
is Kc = 4.9 × 10–2. The value of Kc for the reaction'
2SO2 (g) +O2(g) ⇌ 2SO3 (g) will be

  • 416

  • 2.40 × 10–3

  • 9.8 × 10–2

  • 9.8 × 10–2

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