The basic buffer solution among the following is: 

1. ${\mathrm{NH}}_4\mathrm{Cl}+{\mathrm{NH}}_4\mathrm{OH}$

2. $\mathrm{NaCl}+\mathrm{NaOH}$

3. ${\mathrm{NH}}_4\mathrm{Cl}+{\mathrm{CH}}_3\mathrm{COOH}$

4. ${\mathrm{CH}}_3\mathrm{COONa}+{\mathrm{CH}}_3\mathrm{COOH}$

Conjugate base of hydrazoic acid is: 

1. ${\mathrm{HN}}_3^{-}$

2. ${\mathrm{N}}_2^{-}$

3. Azide ion

4. Nitride ion

Out of ${\mathrm{Ca}}^{2+},\hspace{0.17em}{\mathrm{Al}}^{3+},\hspace{0.17em}{\mathrm{Cr}}^{3+}, {\mathrm{Mg}}^{2+}, \mathrm{and} {\mathrm{Zn}}^{2+},$ the reagents ${\mathrm{NH}}_4\mathrm{Cl}$ and aqueous ${\mathrm{NH}}_3$ will precipitate

1. ${\mathrm{Ca}}^{2+},\hspace{0.17em}{\mathrm{Al}}^{3+}$

2. ${\mathrm{Al}}^{3+}, {\mathrm{Cr}}^{3+}$

3. ${\mathrm{Bi}}^{3+}, {\mathrm{Mg}}^{2+}$

4. ${\mathrm{Mg}}^{2+}, {\mathrm{Zn}}^{2+}$

The pH of 0.1 M solution of the following compounds increases in the order of -

1. $\mathrm{NaCl}<{\mathrm{NH}}_4\mathrm{Cl}<\mathrm{NaCN}<\mathrm{HCl}$

2. $\mathrm{HCl}<{\mathrm{NH}}_4\mathrm{Cl}<\mathrm{NaCl}<\mathrm{NaCN}$

3. $\mathrm{NaCN}<{\mathrm{NH}}_4\mathrm{Cl}<\mathrm{NaCl}<\mathrm{HCl}$

4. $\mathrm{HCl}<\mathrm{NaCl}<\mathrm{NaCN}<{\mathrm{NH}}_4\mathrm{Cl}$

The pK_a of HCN is 9.30. The pH of a solution prepared by mixing 2.5 moles of KCN and 2.5 moles of HCN in water and making up the total volume to 500 ml will be:

Which of the following is an example of a reversible reaction?
1. \(\small{KNO_3(aq) + NaCl(aq) \rightleftharpoons KCl(aq) + NaNO_3(aq)}\)
2. \(\small{2Na(s) + H_2O(l) \rightleftharpoons 2NaOH(aq) + H_2(g)}\)
3. \(\small{AgNO_3(aq) + NaCl(aq) \rightleftharpoons AgCl(s) + NaNO_3(aq)}\)
4. \(\small{Pb{(NO_3)}_2(aq) + 2NaI(aq) \rightleftharpoons PbI_2(s) + 2NaNO_3(aq)}\)

If a solution of 0.1 M NH₄OH and 0.1 M NH₄Cl has pH 9.25, then the pK_b of NH₄OH will be:

At 25°C, the pH of a solution containing 0.10 M sodium acetate and 0.03 M acetic acid will be:

[pK_a value of ${\mathrm{CH}}_3\mathrm{COOH}=4.57$]-

1. 3.24

2. 4.59

3. 5.09

4. 6.67

The ratio of the concentration of salt and acid for preparing a buffer solution of pH 6 by mixing sodium acetate and acetic acid will be: (K_a=10^-5)

1. 1:10

2. 10:1

3. 100:1

4. 1:100

The pH of a solution made by mixing 50 mL of 0.01 M barium hydroxide solution with 50 mL of H₂O is