Common Ion Effect

Q. Factors that affect degree of ionisation include :

1. Dilution
2. Presence of other solutes
3. Nature of electrolyte
4. Nature of solvent

Q. A 50 mL solution of strong acid of pH = 1 is mixed with a 50 mL solution of strong acid of pH = 2. The pH of the mixture will be :
$(lo{g}_{10}5.5=0.74)$

1. 1.76
2. 1.5
3. 1.26
4. 0.74

Q. The dissociation constant for $H_{2}S$ and $H{S}^{-}$ are respectively ${10}^{-7}and{10}^{-13}$. The pH of $0.1M$ aqueous solution of $H_{2}S$ will be :

1. 4
2. 5
3. 3
4. 2.5

Q. The dissociation constant for $H_{2}S$ and $H{S}^{-}$ are respectively ${10}^{-7}and{10}^{-13}$. The pH of $0.1M$ aqueous solution of $H_{2}S$ will be :

1. 4
2. 5
3. 3
4. 2.5

Q. Calculate the $pH$ at which an acid indicator $\left(HIn\right)$ having $K_{In}={10}^{-5}$ changes its colour.
Given, the $HIn$ concentration is ${10}^{-3}M$.

1. $3$
2. $2$
3. $5$
4. $8$

Q. The pH of the $0.10M$ hydrocyanic acid solutions is 5.2. What will be the value of $K_a$ for hydrocyanic acid ?

1. $4.0\times {10}^{-5}$
2. $2.0\times {10}^{-10}$
3. $2.0\times {10}^{-5}$
4. $4.0\times {10}^{-10}$

Q.

The addition of sodium acetate to 0.1 M acetic acid will cause

1. increase in its pH value

2. decrease in its pH value

3. no change in pH value

4. change in pH which cannot be predicted

Q.

Solubility products of $Al(OH{)}_3$ and $Zn(OH{)}_2$ are $2.7\times {10}^{-23}and3.2\times {10}^{-14}$ respectively. If to a solution of 0.1 M each of $A{l}^{3+}andZ{n}^{2+}ions,N{H}_{4}OH$ is added in increasing amounts which of the following will be precipitated first ?

1. $Zn(OH{)}_2$

2. $Al(OH{)}_3$

3. $Bothofthem$

4. $Noneofthem$

Q. If solubility product of $Z{r}_3\left(P{O}_4\right))4$ is denoted by $K_{sp}$ and its molar solubility is denoted by S, then which of the following relation between S and $K_{sp}$ is correct?

1. $S={\left(\frac{K_{sp}}{144}\right)}^{1/6}$
2. $S={\left(\frac{K_{sp}}{6912}\right)}^{1/7}$
3. $S={\left(\frac{K_{sp}}{929}\right)}^{1/9}$
4. $S={\left(\frac{K_{sp}}{216}\right)}^{1/7}$

Q.

The addition of sodium acetate to 0.1 M acetic acid will cause

1. decrease in its pH value

2. increase in its pH value

3. no change in pH value

4. change in pH which cannot be predicted

Q. Calculate pH of a solution which is ${10}^{-1}M$ in HCl & ${10}^{-3}M$ in $C{H}_{3}COOH[K_a=2\times {10}^{-5}]$. Also calculate $\left[H^{+}\right]$ From $C{H}_{3}COOH.$

1. pH=1, $\left[H^{+}\right]=2\times {10}^{-7}$ M
2. pH=7, $\left[H^{+}\right]=3\times {10}^{-6}$ M
3. pH=7, $\left[H^{+}\right]=2\times {10}^{-7}$ M
4. pH=1, $\left[H^{+}\right]=3\times {10}^{-7}$ M

Q.

The addition of ammonium chloride to 0.1 M acetic acid will cause:

1. decrease in its pH value

2. no change in pH value

3. change in pH which cannot be predicted

4. increase in its pH value

Q. Calculate the $pH$ at which a basic indicator $\left(InOH\right)$ with $K_{In}=1\times {10}^{-10}$ changes its colour.
Given : The concentration of indicator is $1\times {10}^{-2}M$.

1. 8
2. 2
3. 10
4. 4

Q. An indicator has $p{K}_{in}=\mathrm{5.3.}$ In a certain solution, this indicator is found to be $20\%$ ionised. Calculate the pH of the solution?

1. $1.6$
2. $6$
3. $5.3$
4. $4.7$

Q. Which of the following statement is incorrect ?

${\Lambda }_m$ - Molar conductivity
${\Lambda }_m^0$ - Limiting molar conductivity
$C$ - concentration of electrolyte

Q. The dissociation constant of $0.01MC{H}_{3}COOH$ is $1.8\times {10}^{-5}$ then calculate $C{H}_{3}CO{O}^{-}$ concentration in $0.1MHCl$ solution.

1. $1.8\times {10}^{-6}mol{L}^{-1}$
2. $1.8\times {10}^{-4}mol{L}^{-1}$
3. $2.8\times {10}^{-6}mol{L}^{-1}$
4. $2.4\times {10}^{-4}mol{L}^{-1}$

Q. For an aqueous solution of a weak electrolyte $C{H}_{3}COOH$, how does the presence of $C{H}_{3}COONa$ affect its degree of ionisation?

1. The degree of ionisation decreases.
2. The degree of ionisation increases.
3. $C{H}_{3}COOH$ acts as a strong acid.
4. The degree of ionisation remains same.

Q. In the dissociation of $N{H}_{4}OH$,
$N{H}_{4}OH\left(aq\right)\rightleftharpoons N{H}_4^{+}\left(aq\right)+O{H}^{-}\left(aq\right)$
If $N{H}_{4}Cl$ is added to it, how will the $pH$ for the $N{H}_{4}OH$ solution change?

1. pH increases.
2. pH decreases.
3. pH remains the same.
4. pH may increase or decrease depending on the concentration of $N{H}_{4}Cl$ added.

Q. If the solubility of $Ca{F}_2$ in water at ${18}^{\circ }C$ is $2.05\times {10}^{-4}mol{L}^{-1}$. Calculate its solubility product at the given temperature.

1. $3.45\times {10}^{-11}$
2. $4.45\times {10}^{-12}$
3. $5.45\times {10}^{-10}$
4. $6.66\times {10}^{-9}$

Q. Acetic acid dissociates in an equilibrium with acetate ion and proton. When a small amount of HCl is added:

1. the equilibrium constant will increase

2. acetate ion concentration decreases

3. acetate ion concentration increases

4. the equilibrium constant will decrease

Q.

$0.1mol$ of methyl amine ($K_b$ = $5\times {10}^{-4}$) is mixed with $0.08mol$ of $HCl$ and the solution is diluted to $1litre$. The hydrogen ion concentration of the resulting solution is:

1. $\left[H^{+}\right]$ = $3.68\times {10}^{-11}M$

2. $\left[H^{+}\right]$ = $1.79\times {10}^{-11}M$

3. $\left[H^{+}\right]$ = $6.53\times {10}^{-11}M$

4. $\left[H^{+}\right]$ = $8\times {10}^{-11}M$

Q. The pH of the solution when $0.2molHCl$ is added to 1 L of solution containing 0.1 M of of $C{H}_{3}CO{O}^{-}$ (acetate ion) is :
$K_a=1.8\times {10}^{-5}$ and Volume= 1 L

1. 1
2. 2
3. 3
4. 4

Q. A solution contains 0.1 M $H_{2}S$ and 0.3 M HCl. Calculate the conc. of $S^{2-}$ and $H{S}^{-}$ ions in solution, Given $K_{a_1}$ and $K_{a_2}$ for $H_{2}S$ are ${10}^{-7}$ and $1.3\times {10}^{-13}$ respectively.

1. $1.43\times {10}^{-20}M,3.3\times {10}^{-8}M$
2. $1.43\times {10}^{-10}M,3.3\times {10}^{-4}M$
3. $2.83\times {10}^{-19}M,3.3\times {10}^{-8}M$
4. $1.43\times {10}^{-19}M,1.65\times {10}^{-8}M$

Q.

The solubilities of $AgCl$ in water, 0.01 M $CaC{l}_2$, 0.01 M $NaCl$ and 0.05 M $AgN{O}_3$ are denoted by $S_1,S_2,S_3,S_4$ respectively. Which of the following relationships are correct? $K_{sp}=1.8\times {10}^{-10}$

1. $S_1>S_2$
2. $S_2>S_3$
3. $S_3>S_4$
4. $S_4>S_1$

Q. In the dissociation of $N{H}_{4}OH$,
$N{H}_{4}OH\left(aq\right)\rightleftharpoons N{H}_4^{+}\left(aq\right)+O{H}^{-}\left(aq\right)$
If $N{H}_{4}Cl$ is added to it, how will the $pH$ for the $N{H}_{4}OH$ solution change?

1. pH remains the same.
2. pH increases.
3. pH decreases.
4. pH may increase or decrease depending on the concentration of $N{H}_{4}Cl$ added.

Q. Factors that affect degree of ionisation include :

1. Dilution
2. Presence of other solutes
3. Nature of electrolyte
4. Nature of solvent

Q. In which of the following, dissociation of $N{H}_{4}OH$ will be minimised

1. $NaCl$
2. $H_{2}O$
3. $NaOH$
4. $N{H}_{4}Cl$