The mixture that can act like a buffer is:

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

2. ${\mathrm{NH}}_4{\mathrm{NO}}_3+{\mathrm{NH}}_4\mathrm{OH}$

3. $50<mspace\; width="1em"></mspace>\mathrm{ml}<mspace\; width="1em"></mspace>0.1<mspace\; width="1em"></mspace>\mathrm{m}<mspace\; width="1em"></mspace>\mathrm{NaCN}+30<mspace\; width="1em"></mspace>\mathrm{ml}<mspace\; width="1em"></mspace>0.1<mspace\; width="1em"></mspace>\mathrm{m}<mspace\; width="1em"></mspace>\mathrm{HCl}$

4. All of the above

An acid buffer solution can be prepared by mixing the solutions of:

1. Sodium chloride and sodium hydroxide

2. Sulphuric acid and sodium sulphate

3. Ammonium chloride and ammonium nitrate

4. Ammonium acetate and acetic acid

Which of the following combinations can be used to prepare a buffer solution?

I. Sodium acetate and acetic acid in water

II. Sodium acetate and hydrochloric acid in water

III. Ammonia and ammonium chloride in water

IV. Ammonia and sodium hydroxide in water.

1. I, III, IV

2. III, IV

3. I, II, IV

4. I,  III

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. \({HN_3}^-\)${}_{}^{}$

2. \(N_2^-\)   ${\mathrm{}}_{}^{}$

3. \(N_3^-\) 
4. \({N^3}^-\)

Which of the following cations will form precipitates when treated with a mixture of ammonium chloride (NH₄Cl) and aqueous ammonia (NH₃)?
\(\mathrm{Ca}^{2+}, \mathrm{Al}^{3+}, \mathrm{Cr}^{3+}, \mathrm{Mg}^{2+}, \mathrm{Zn}^{2+} \)
1. \(\mathrm{Ca}^{2+}, \mathrm{Al}^{3+} \)
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?

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: