A physician wishes to prepare a buffer solution at pH=3.58 that efficiently resist changes in pH yet contains only small concetration of the buffering agents. Which one of the following weak acid together with its sodium salt would be best to use ?           [1997]

1. m-chlorobenzoic acid (pK_a = 3.98)

2. p-chlorocinnamic acid (pK_a = 4.41)

3. 2,5-dihydroxy benzoic acid (pK_a = 2.97)

4. Acetoacetic acid (pK_a = 3.58)

Which one of the following is true for any diprotic acid, H₂X?
1. K_a2 = K_a1
2. K_a1 > K_a2
3. K_a1 < K_a2
4. \(K_{a1}=\frac{1}{K_{a2}}\)

One mole of ethyl alcohol was treated with one mole of acetic acid at 25$°$C. 2/3 of the acid changes into ester at equilibrium. The equilibrium constant for the reaction will be:

1. 1                   

2. 2

3. 3                   

4. 4

For a given solution pH = 6.9 at 60$°$C, where K_w=10^-12. The solution is:

1. acidic                                         

2. basic

3. neutral                                         

4. unpredictable

In a buffer solution containing equal concentration of B^- and H B, the K_b for B^- is 10^-10. The pH of buffer solution is 

1. 10

2. 7

3. 6

4. 4

Aqueous solution of acetic acid contains                                                   

1. CH₃COO^- and H⁺

2. CH₃COO^-, H₃O⁺ and CH₃COOH

3. CH₃COO^-, H₃O⁺ and H⁺

4. CH₃COOH, CH₃COO^- and H⁺

The equilibrium, 2SO₂ (g) + O₂ (g) $\rightleftharpoons$2SO₃ (g)

shifts forward if:

1. a catalyst is used

2. an absorbent is used to remove SO₃ as soon as it is formed

3. small amounts of reactants are used

4. none of the above

The pH of blood is maintained by CO₂ by and H₂CO₃ in the body and chemical constituents of blood. This phenomenon is called:

1. colloidal                           

2. buffer action

3. acidic                               

4. salt balance

Incorrect statement among the following is: 

1. Addition of one drop of concentrated HCl in NH₄OH solution decreases pH of the solution.

2. A solution of the mixture of one equivalent of each of CH₃COOH and NaOH has a pH of 7

3. pH of pure neutral water is not zero.

4. A cold and concentrated H₂SO₄ has lower H⁺ ion concentration than a dilute solution of H₂SO₄ 

The rate constants for forward and backward reaction of hydrolysis is ester are 1.1 x10^-2 and 1.5x10^-3 per minute. Equilibrium constant for the reaction,                                                              

 CH₃COOC₂H₅ + H⁺ $\rightleftharpoons$ CH₃COOH + C₂H₅OH is

1. 4.33           

2. 5.33           

3. 6.33         

4. 7.33