The pH of a 0.05 M aqueous solution of diethylamine is 12. Its K_b value will be:

1. $2\times {10}^{-3}$

2. $2.5\times {10}^{-3}$

3. $3\times {10}^{-3}$

4. $4.5\times {10}^{-3}$

K_a for HCN is $5\times {10}^{-10}$ at $25°\mathrm{C}$. For maintaining a constant pH of 9, the volume of 5 M KCN solution required to be added to 10 mL of 2 M HCN solution is-

1. 2 mL

2. 3 mL

3. 4.2 mL

4. 5.6 mL

Which of the following compounds are in the correct sequence in terms of relative basic strength?

1. \(C_{2} H_{5} O^{-} > CH \equiv C^{-} > \left(OH\right)^{-}\)

2. \(CH \equiv C^{-} >(OH)^{-} > C_{2} H_{5} O^{-}\)

3. \(CH \equiv C^{-} > C_{2} H_{5} O^{-} > \left(OH\right)^{-}\)

4. \(C_{2} H_{5} O^{-} > \left(OH\right)^{-} > CH \equiv C^{-}\)

The concentration of CH₃COOH that will have the same [H⁺] as obtained from 10^-2 M HCOOH, is-

$\left(\mathrm{Ka}\right({\mathrm{CH}}_3\mathrm{COOH})={10}^{-5},$ $\mathrm{Ka}\left(\mathrm{HCOOH}\right)={10}^{-4})$

1. 10 M

2. 5 M

3. 10^-1 M

4. 6 M

What happens when NH₄Cl is added to an aqueous solution of NH₄OH?

1. Concentration of $\left[{\mathrm{OH}}^{-}\right]$ ions decreases.

2. Concentration of $\left[{\mathrm{OH}}^{-}\right]$ ions increases.

3. Concentration of $\left[{\mathrm{NH}}_4^{+}\right]$ ions as well as concentration $\left[{\mathrm{OH}}^{-}\right]$ ions increase.

4. Concentration of $\left[{\mathrm{NH}}_4^{+}\right]$ ions decreases.

A solution of benzoic acid (a weak monobasic acid) is titrated with NaOH. The pH of the solution is 4.2 when half of the acid is neutralized. The dissociation constant of the acid will be:

1. $3.2\times {10}^{-5}$

2. $6.42\times {10}^{-4}$

3. $6.31\times {10}^{-5}$

4. $8.7\times {10}^{-8}$

The mixture that shows the maximum buffer capacity is:

1. $0.1<mspace\; width="1em"></mspace>\mathrm{M}<mspace\; width="1em"></mspace>{\mathrm{CH}}_3\mathrm{COOH}+0.2<mspace\; width="1em"></mspace>\mathrm{M}\hspace{0.17em}{\mathrm{CH}}_3\mathrm{COONa}$

2. $0.1<mspace\; width="1em"></mspace>\mathrm{M}<mspace\; width="1em"></mspace>{\mathrm{CH}}_3\mathrm{COOH}+0.15<mspace\; width="1em"></mspace>\mathrm{M}\hspace{0.17em}{\mathrm{CH}}_3\mathrm{COONa}$

3. $0.05<mspace\; width="1em"></mspace>\mathrm{M}<mspace\; width="1em"></mspace>{\mathrm{CH}}_3\mathrm{COOH}+0.15<mspace\; width="1em"></mspace>\mathrm{M}\hspace{0.17em}{\mathrm{CH}}_3\mathrm{COONa}$

4. $0.1<mspace\; width="1em"></mspace>\mathrm{M}<mspace\; width="1em"></mspace>{\mathrm{CH}}_3\mathrm{COOH}+0.12<mspace\; width="1em"></mspace>\mathrm{M}\hspace{0.17em}{\mathrm{CH}}_3\mathrm{COONa}$

The pH of a solution containing 0.1 mol of CH₃COOH, 0.2 mol of CH₃COONa, and 0.05 mol of NaOH in 1 L of solution is-

(pK_a of CH₃COOH=4.74 and log 5=0.7)

1. 4.56

2. 5.44

3. 5.04

4. 3.74

Which of the following is an amphiprotic (can accept and give protons) ion?

1. ${\mathrm{HPO}}_3^{-}$

2. ${\mathrm{H}}_2{\mathrm{PO}}_2^{-}$

3. ${\mathrm{H}}_3{\mathrm{PO}}_4$

4. ${\mathrm{H}}_2{\mathrm{PO}}_4^{-}$

A buffer solution is prepared by mixing 10 mL of 1.0 M acetic acid with 20 mL of 0.5 M sodium acetate which is then diluted
to 100 mL with distilled water. If the pK_a of ${\mathrm{CH}}_3\mathrm{COOH}$ is 4.76, the pH of the buffer solution prepared is -
1. 5.21

2. 4.76

3. 4.34

4. 5.35