Hydrolysis of salts — practice questions

Question 1 · difficulty L3 · understanding

Given below are two statements : Statement (I) : Aqueous solution of ammonium carbonate is basic. Statement (II) : Acidic/basic nature of salt solution of a salt of weak acid and weak base depends on $$K_a$$ and $$K_b$$ value of acid and the base forming it. In the light of the above statements, choose the most appropriate answer from the options given below :

• A. Both Statement I and Statement II are correct
• B. Statement I is correct but Statement II is incorrect
• C. Both Statement I and Statement II are incorrect
• D. Statement I is incorrect but Statement II is correct

Question 2 · difficulty L3 · understanding

$$20 \mathrm{~mL}$$ of $$0.1\, \mathrm{M} \,\mathrm{NH}_{4} \mathrm{OH}$$ is mixed with $$40 \mathrm{~mL}$$ of $$0.05 \mathrm{M} \mathrm{HCl}$$. The $$\mathrm{pH}$$ of the mixture is nearest to : (Given : $$\mathrm{K}_{\mathrm{b}}\left(\mathrm{NH}_{4} \mathrm{OH}\right)=1 \times 10^{-5}, \log 2=0.30, \log 3=0.48, \log 5=0.69, \log 7=0.84, \log 11= 1.04)$$

• A. 3.2
• B. 4.2
• C. 5.2
• D. 6.2

Question 3 · difficulty L3 · understanding

Given below are two statements : One is labelled as Assertion A and the other labelled as reason R Assertion A : During the boiling of water having temporary hardness, Mg(HCO 3 ) 2 is converted to MgCO 3 . Reason R : The solubility product of Mg(OH) 2 is greater than that of MgCO 3 . In the light of the above statements, choose the most appropriate answer from the options given below :

• A. Both A and R are true but R is not the correct explanation of A
• B. A is true but R is false
• C. Both A and R are true and R is the correct explanation of A
• D. A is false but R is true

Question 4 · difficulty L3 · understanding

The percentage dissociation of a salt $\left(\mathrm{MX}_3\right)$ solution at given temperature (van't Hoff factor $\mathrm{i}=2$ ) is ___________ %(Nearest integer)

Question 5 · difficulty L3 · understanding

The observed and normal molar masses of compound $\mathrm{MX}_2$ are 65.6 and 164 respectively. The percent degree of ionisation of $\mathrm{MX}_2$ is __________%. (Nearest integer)

Question 6 · difficulty L3 · understanding

The dissociation constant of a substituted benzoic acid at 25$$^\circ$$C is 1.0 $$\times$$ 10$$^{-4}$$. The pH of a 0.01 M solution of its sodium salt is __________.

Question 7 · difficulty L3 · understanding

2.5 mL of $$\frac{2}{5}$$M weak monoacidic base (K$$_b$$ = 1 $$\times$$ 10$$^{-12}$$ at 25$$^\circ$$C) is titrated with $$\frac{2}{15}$$M HCl in water at 25$$^\circ$$C. The concentration of H$$^+$$ at equivalence point is (K$$_w$$ = 1 $$\times$$ 10$$^{-14}$$ at 25$$^\circ$$C).

• A. 3.7 $$\times$$ 10$$^{-13}$$ M
• B. 3.2 $$\times$$ 10$$^{-7}$$ M
• C. 3.2 $$\times$$ 10$$^{-2}$$ M
• D. 2.7 $$\times$$ 10$$^{-2}$$ M