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 are Lewis acids?

(i) \(BF_3\)

(ii) \(H_2O\) ${\mathrm{}}_{}$

(iii) \(HSO_4^-\)${}_{}^{}$

(iv) \(SO_3\)
 

1. (i) and (iii)

2. (i) and (ii)

3. (i) and (iv)

4. (iii) and (iv)

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. \(\mathrm{Mg}^{2+}, \mathrm{Zn}^{2+}\)

Find the least soluble salt among the following.

The dissociation constant of a substituted benzoic acid at $25°\mathrm{C}$ is $1\times {10}^{-4}.$ The pH of a 0.01 M solution of its sodium salt of benzoic acid is:

Which one of the following is true for any diprotic acid, ${\mathrm{H}}_2\mathrm{X}$?

1. ${\mathrm{Ka}}_1={\mathrm{Ka}}_2$

2. ${\mathrm{Ka}}_2>{\mathrm{Ka}}_1$

3. ${\mathrm{Ka}}_1>{\mathrm{Ka}}_2$

4. ${\mathrm{Ka}}_2=1/{\mathrm{Ka}}_1$

Find the relationship between the solubility product (Lₛ) and molar solubility (s) of a sparingly soluble salt AₚBq.

1. ${\mathrm{L}}_{\mathrm{s}}={\mathrm{s}}^{\mathrm{p}+\mathrm{q}}.{\mathrm{p}}^p.{\mathrm{q}}^{\mathrm{q}}$

2. ${\mathrm{L}}_{\mathrm{s}}={\mathrm{s}}^{\mathrm{p}+\mathrm{q}}.{\mathrm{p}}^{\mathrm{q}}.{\mathrm{q}}^{\mathrm{q}}$

3. ${\mathrm{L}}_{\mathrm{s}}={\mathrm{s}}^{\mathrm{pq}}{\mathrm{p}}^{\mathrm{q}}{\mathrm{q}}^{\mathrm{q}}$

4. ${\mathrm{L}}_{\mathrm{s}}={\mathrm{s}}^{\mathrm{pq}}.{\left(\mathrm{pq}\right)}^{\mathrm{p}+\mathrm{q}}$

Find the correct order of acid strength for acids A, B, and C having pKa values 4.3, 3.3, and 5.5, respectively.

1. A>B>C

2. C>A>B

3. B>A>C

4. C>B>A