QBManager

Ionic Equilibrium

229566 The conductivity of a $0.05 M$ solution of a weak monobasic acid is $10^{- 3} S {cm}^{- 1}$ . If $λ_{m}$ for weak acid is $500 S {cm}^{2} {mol}^{- 1}$ , calculate $K_{a}$ of weak monobasic acid:

1

8 \times 10^{- 5}

2

4 \times 10^{- 6}

3

16 \times 10^{- 7}

4

14 \times 10^{- 8}

Explanation:

Given that, $C = 0.05 M, k = 10^{- 5} S {cm}^{- 1}$
$\begin{aligned} λ_{m}^{\infty} = 500 {Scm}^{2} {mol}^{- 1} \\ K_{a} = {Ca}^{2} \end{aligned}$
We have to find $α$ .
$\begin{aligned} α = \frac{λ_{m}^{c}}{λ_{m}^{c}} \\ ∵ λ_{m}^{c} = \frac{1000 \times k}{C} \\ = \frac{1000 \times 10^{- 3}}{0.05} \\ λ_{m}^{c} = 20 S {cm}^{2} {mol}^{- 1} \\ α = \frac{20 {Scm}^{2} {mol}^{- 1}}{500 {Scm}^{2} {mol}^{- 1}} = 0.04 \\ K_{a} = {Ca}^{2} \\ K_{a} = 0.05 \times (0.04)^{2} \\ = 0.00008 \\ K_{a} = 8 \times 10^{- 5} \end{aligned}$

AIIMS 26 May 2019 (Evening)

Ionic Equilibrium

229567 Which of the following is incorrect about $K_{2} {Cr}_{2} O_{7}$ ?

1 It can be prepared from

K_{2} {CrO}_{4}

.

2 It is used in redox titrations.

3 It is stable in both acid \& base.

4 It is orange in colour.

Explanation:

Exp:
- Colour of $K_{2} {Cr}_{2} O_{7}$ is orange
- $2 {Cr}_{4}^{- 2} \overset{In acidic medium}{H +} {Cr}_{2} O_{7}^{2 -} + H_{2} O$
(Chromate ion) (Dichromate ion)
- $K_{2} {Cr}_{2} O_{7}$ is used in redox titrations.
- It is stable in both acid \& base this statement is incorrect about $K_{2} {Cr}_{2} O_{7}$ .

AIIMS 26 May 2019(Evening)

Ionic Equilibrium

229572 Assertion : $K O H$ is more soluble in water than $NaOH$ .
**Reason :** $NaOH$ is a stronger base than $KOH$ .

1 If both Assertion and Reason are correct and the Reason is the correct explanation of Assertion.

2 If both Assertion and Reason are correct, but Reason is not the correct explanation of Assertion.

3 If Assertion if correct but Reason is incorrect.

4 If both the Assertion and Reason are incorrect.

Explanation:

$KOH$ is more soluble in water than $NaOH$ .
The ionic size of ${Na}^{+}$ is smaller than $K^{+}$ . Hence attractive force between ${Na}^{+}$ and $OH$ is relatively strong and so ionisation of $NaOH$ is lower than $KOH$ which makes $NaOH$ a weaker base than $KOH$ .

AIIMS-(2011)

Ionic Equilibrium

229573 Assertion : Addition of silver ions to a mixture of aqueous sodium chloride and sodium bromide solution will first precipitate $AgBr$ rather than AgC1.
**Reason:** $K_{5 p}$ of $AgCl > K_{5 p}$ of $AgBr$ .

1 If both Assertion and Reason are correct and the Reason is the correct explanation of Assertion.

2 If both assertion and Reason are correct, but Reason is not the correct explanation of assertion.

3 If Assertion is correct but Reason is incorrect.

4 If both the Assertion and Reason are incorrect.

Explanation:

We know that,
The solubility product of $AgBr = 5 \times 10^{- 13}$ and $AgCl =$ $5 \times 10^{- 10}$
Hence, $K_{sp}$ of $AgCl < K_{sp}$ of $AgBr$
Hence, when we add silver ion to a mixture of aqueous sodium chloride and sodium bromide solution, $AgBr$ will percipitate first.

AIIMS-(2016

Ionic Equilibrium

229566 The conductivity of a $0.05 M$ solution of a weak monobasic acid is $10^{- 3} S {cm}^{- 1}$ . If $λ_{m}$ for weak acid is $500 S {cm}^{2} {mol}^{- 1}$ , calculate $K_{a}$ of weak monobasic acid:

1

8 \times 10^{- 5}

2

4 \times 10^{- 6}

3

16 \times 10^{- 7}

4

14 \times 10^{- 8}

Explanation:

Given that, $C = 0.05 M, k = 10^{- 5} S {cm}^{- 1}$
$\begin{aligned} λ_{m}^{\infty} = 500 {Scm}^{2} {mol}^{- 1} \\ K_{a} = {Ca}^{2} \end{aligned}$
We have to find $α$ .
$\begin{aligned} α = \frac{λ_{m}^{c}}{λ_{m}^{c}} \\ ∵ λ_{m}^{c} = \frac{1000 \times k}{C} \\ = \frac{1000 \times 10^{- 3}}{0.05} \\ λ_{m}^{c} = 20 S {cm}^{2} {mol}^{- 1} \\ α = \frac{20 {Scm}^{2} {mol}^{- 1}}{500 {Scm}^{2} {mol}^{- 1}} = 0.04 \\ K_{a} = {Ca}^{2} \\ K_{a} = 0.05 \times (0.04)^{2} \\ = 0.00008 \\ K_{a} = 8 \times 10^{- 5} \end{aligned}$

AIIMS 26 May 2019 (Evening)

Ionic Equilibrium

229567 Which of the following is incorrect about $K_{2} {Cr}_{2} O_{7}$ ?

1 It can be prepared from

K_{2} {CrO}_{4}

.

2 It is used in redox titrations.

3 It is stable in both acid \& base.

4 It is orange in colour.

Explanation:

Exp:
- Colour of $K_{2} {Cr}_{2} O_{7}$ is orange
- $2 {Cr}_{4}^{- 2} \overset{In acidic medium}{H +} {Cr}_{2} O_{7}^{2 -} + H_{2} O$
(Chromate ion) (Dichromate ion)
- $K_{2} {Cr}_{2} O_{7}$ is used in redox titrations.
- It is stable in both acid \& base this statement is incorrect about $K_{2} {Cr}_{2} O_{7}$ .

AIIMS 26 May 2019(Evening)

Ionic Equilibrium

229572 Assertion : $K O H$ is more soluble in water than $NaOH$ .
**Reason :** $NaOH$ is a stronger base than $KOH$ .

1 If both Assertion and Reason are correct and the Reason is the correct explanation of Assertion.

2 If both Assertion and Reason are correct, but Reason is not the correct explanation of Assertion.

3 If Assertion if correct but Reason is incorrect.

4 If both the Assertion and Reason are incorrect.

Explanation:

$KOH$ is more soluble in water than $NaOH$ .
The ionic size of ${Na}^{+}$ is smaller than $K^{+}$ . Hence attractive force between ${Na}^{+}$ and $OH$ is relatively strong and so ionisation of $NaOH$ is lower than $KOH$ which makes $NaOH$ a weaker base than $KOH$ .

AIIMS-(2011)

Ionic Equilibrium

229573 Assertion : Addition of silver ions to a mixture of aqueous sodium chloride and sodium bromide solution will first precipitate $AgBr$ rather than AgC1.
**Reason:** $K_{5 p}$ of $AgCl > K_{5 p}$ of $AgBr$ .

1 If both Assertion and Reason are correct and the Reason is the correct explanation of Assertion.

2 If both assertion and Reason are correct, but Reason is not the correct explanation of assertion.

3 If Assertion is correct but Reason is incorrect.

4 If both the Assertion and Reason are incorrect.

Explanation:

We know that,
The solubility product of $AgBr = 5 \times 10^{- 13}$ and $AgCl =$ $5 \times 10^{- 10}$
Hence, $K_{sp}$ of $AgCl < K_{sp}$ of $AgBr$
Hence, when we add silver ion to a mixture of aqueous sodium chloride and sodium bromide solution, $AgBr$ will percipitate first.

AIIMS-(2016

Ionic Equilibrium

229566 The conductivity of a $0.05 M$ solution of a weak monobasic acid is $10^{- 3} S {cm}^{- 1}$ . If $λ_{m}$ for weak acid is $500 S {cm}^{2} {mol}^{- 1}$ , calculate $K_{a}$ of weak monobasic acid:

1

8 \times 10^{- 5}

2

4 \times 10^{- 6}

3

16 \times 10^{- 7}

4

14 \times 10^{- 8}

Explanation:

Given that, $C = 0.05 M, k = 10^{- 5} S {cm}^{- 1}$
$\begin{aligned} λ_{m}^{\infty} = 500 {Scm}^{2} {mol}^{- 1} \\ K_{a} = {Ca}^{2} \end{aligned}$
We have to find $α$ .
$\begin{aligned} α = \frac{λ_{m}^{c}}{λ_{m}^{c}} \\ ∵ λ_{m}^{c} = \frac{1000 \times k}{C} \\ = \frac{1000 \times 10^{- 3}}{0.05} \\ λ_{m}^{c} = 20 S {cm}^{2} {mol}^{- 1} \\ α = \frac{20 {Scm}^{2} {mol}^{- 1}}{500 {Scm}^{2} {mol}^{- 1}} = 0.04 \\ K_{a} = {Ca}^{2} \\ K_{a} = 0.05 \times (0.04)^{2} \\ = 0.00008 \\ K_{a} = 8 \times 10^{- 5} \end{aligned}$

AIIMS 26 May 2019 (Evening)

Ionic Equilibrium

229567 Which of the following is incorrect about $K_{2} {Cr}_{2} O_{7}$ ?

1 It can be prepared from

K_{2} {CrO}_{4}

.

2 It is used in redox titrations.

3 It is stable in both acid \& base.

4 It is orange in colour.

Explanation:

Exp:
- Colour of $K_{2} {Cr}_{2} O_{7}$ is orange
- $2 {Cr}_{4}^{- 2} \overset{In acidic medium}{H +} {Cr}_{2} O_{7}^{2 -} + H_{2} O$
(Chromate ion) (Dichromate ion)
- $K_{2} {Cr}_{2} O_{7}$ is used in redox titrations.
- It is stable in both acid \& base this statement is incorrect about $K_{2} {Cr}_{2} O_{7}$ .

AIIMS 26 May 2019(Evening)

Ionic Equilibrium

229572 Assertion : $K O H$ is more soluble in water than $NaOH$ .
**Reason :** $NaOH$ is a stronger base than $KOH$ .

1 If both Assertion and Reason are correct and the Reason is the correct explanation of Assertion.

2 If both Assertion and Reason are correct, but Reason is not the correct explanation of Assertion.

3 If Assertion if correct but Reason is incorrect.

4 If both the Assertion and Reason are incorrect.

Explanation:

$KOH$ is more soluble in water than $NaOH$ .
The ionic size of ${Na}^{+}$ is smaller than $K^{+}$ . Hence attractive force between ${Na}^{+}$ and $OH$ is relatively strong and so ionisation of $NaOH$ is lower than $KOH$ which makes $NaOH$ a weaker base than $KOH$ .

AIIMS-(2011)

Ionic Equilibrium

229573 Assertion : Addition of silver ions to a mixture of aqueous sodium chloride and sodium bromide solution will first precipitate $AgBr$ rather than AgC1.
**Reason:** $K_{5 p}$ of $AgCl > K_{5 p}$ of $AgBr$ .

1 If both Assertion and Reason are correct and the Reason is the correct explanation of Assertion.

2 If both assertion and Reason are correct, but Reason is not the correct explanation of assertion.

3 If Assertion is correct but Reason is incorrect.

4 If both the Assertion and Reason are incorrect.

Explanation:

We know that,
The solubility product of $AgBr = 5 \times 10^{- 13}$ and $AgCl =$ $5 \times 10^{- 10}$
Hence, $K_{sp}$ of $AgCl < K_{sp}$ of $AgBr$
Hence, when we add silver ion to a mixture of aqueous sodium chloride and sodium bromide solution, $AgBr$ will percipitate first.

AIIMS-(2016

Ionic Equilibrium

229566 The conductivity of a $0.05 M$ solution of a weak monobasic acid is $10^{- 3} S {cm}^{- 1}$ . If $λ_{m}$ for weak acid is $500 S {cm}^{2} {mol}^{- 1}$ , calculate $K_{a}$ of weak monobasic acid:

1

8 \times 10^{- 5}

2

4 \times 10^{- 6}

3

16 \times 10^{- 7}

4

14 \times 10^{- 8}

Explanation:

Given that, $C = 0.05 M, k = 10^{- 5} S {cm}^{- 1}$
$\begin{aligned} λ_{m}^{\infty} = 500 {Scm}^{2} {mol}^{- 1} \\ K_{a} = {Ca}^{2} \end{aligned}$
We have to find $α$ .
$\begin{aligned} α = \frac{λ_{m}^{c}}{λ_{m}^{c}} \\ ∵ λ_{m}^{c} = \frac{1000 \times k}{C} \\ = \frac{1000 \times 10^{- 3}}{0.05} \\ λ_{m}^{c} = 20 S {cm}^{2} {mol}^{- 1} \\ α = \frac{20 {Scm}^{2} {mol}^{- 1}}{500 {Scm}^{2} {mol}^{- 1}} = 0.04 \\ K_{a} = {Ca}^{2} \\ K_{a} = 0.05 \times (0.04)^{2} \\ = 0.00008 \\ K_{a} = 8 \times 10^{- 5} \end{aligned}$

AIIMS 26 May 2019 (Evening)

Ionic Equilibrium

229567 Which of the following is incorrect about $K_{2} {Cr}_{2} O_{7}$ ?

1 It can be prepared from

K_{2} {CrO}_{4}

.

2 It is used in redox titrations.

3 It is stable in both acid \& base.

4 It is orange in colour.

Explanation:

Exp:
- Colour of $K_{2} {Cr}_{2} O_{7}$ is orange
- $2 {Cr}_{4}^{- 2} \overset{In acidic medium}{H +} {Cr}_{2} O_{7}^{2 -} + H_{2} O$
(Chromate ion) (Dichromate ion)
- $K_{2} {Cr}_{2} O_{7}$ is used in redox titrations.
- It is stable in both acid \& base this statement is incorrect about $K_{2} {Cr}_{2} O_{7}$ .

AIIMS 26 May 2019(Evening)

Ionic Equilibrium

229572 Assertion : $K O H$ is more soluble in water than $NaOH$ .
**Reason :** $NaOH$ is a stronger base than $KOH$ .

1 If both Assertion and Reason are correct and the Reason is the correct explanation of Assertion.

2 If both Assertion and Reason are correct, but Reason is not the correct explanation of Assertion.

3 If Assertion if correct but Reason is incorrect.

4 If both the Assertion and Reason are incorrect.

Explanation:

$KOH$ is more soluble in water than $NaOH$ .
The ionic size of ${Na}^{+}$ is smaller than $K^{+}$ . Hence attractive force between ${Na}^{+}$ and $OH$ is relatively strong and so ionisation of $NaOH$ is lower than $KOH$ which makes $NaOH$ a weaker base than $KOH$ .

AIIMS-(2011)

Ionic Equilibrium

229573 Assertion : Addition of silver ions to a mixture of aqueous sodium chloride and sodium bromide solution will first precipitate $AgBr$ rather than AgC1.
**Reason:** $K_{5 p}$ of $AgCl > K_{5 p}$ of $AgBr$ .

1 If both Assertion and Reason are correct and the Reason is the correct explanation of Assertion.

2 If both assertion and Reason are correct, but Reason is not the correct explanation of assertion.

3 If Assertion is correct but Reason is incorrect.

4 If both the Assertion and Reason are incorrect.

Explanation:

We know that,
The solubility product of $AgBr = 5 \times 10^{- 13}$ and $AgCl =$ $5 \times 10^{- 10}$
Hence, $K_{sp}$ of $AgCl < K_{sp}$ of $AgBr$
Hence, when we add silver ion to a mixture of aqueous sodium chloride and sodium bromide solution, $AgBr$ will percipitate first.

AIIMS-(2016

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