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41.
In which of the following mixed aqueous solutions, pH =pK_aat equilibrium?
(1) 100 mL of 0.1 M CH₃COOH +100mL 0.1 M CH₃COONa.
(2) 100 mL of 0.1 M CH₃COOH + 50 mL of 0.1 M NaOH.
(3) 100 mL of 0.1 M CH₃COOH + 100 mL of 0.1 M NaOH.
(4) 100 mL of 0.1 M CH₃COOH + 100 mL of 0.1 M NH_3.

(1) is correct

(2) is correct

(3) is correct

Both (1) and (2) are correct

(1) is correct

(2) is correct

Both (1) and (2) are correct

$pH of buffer solutions is given by pH = {pK}_{a} + \log \frac{[salt]}{[acid]} (1) {CH}_{3} COOH and {CH}_{3} COONa 100 \times 0.1 100 \times 0.1 No . of milimoles = 10 = 10 \cdot : [salt] = [acid] = 10, pH = {pK}_{a} + \log \frac{10}{10} pH = {pK}_{a} (2) \underset{100 \times 0.1}{{CH}_{3} COOH} + \underset{50 \times 0.1}{NaOH} \to {CH}_{3} COONa + H_{2} O Initial = 10 5 0 0 Final = 5 0 5 0 [salt] = [acid] = 5, pH = {pK}_{a} + \log \frac{5}{5} therefore pH = {pK}_{a} (3) \underset{100 \times 0.1}{{CH}_{3} COOH} + \underset{50 \times 0.1}{NaOH} \to {CH}_{3} COONa + H_{2} O Initial = 10 10 0 0 Final = 0 0 10 10 [salt] = 10 and [acid] = 0 pH = {pK}_{a} + \log \frac{10}{0} therefore pH = {pK}_{a} (4) {CH}_{3} COOH + {NH}_{3} \to {CH}_{3} {COONH}_{4} Initial = 10 10 \to No buffer action Final due to weak {CH}_{3} {COONH}_{4} salt pH \neq {pK}_{a}$

42.

Consider the following salts : NaCl, HgCl₂, Hg₂Cl₂, CuCl₂, CuCl and AgCl.

Identify the correct set of insoluble salts in water.

Hg₂Cl₂, CuCl, AgCl
HgCl₂, CuCl_, AgCl
Hg₂Cl₂, CuCl₂, AgCl
Hg₂Cl₂, CuCl, NaCl

43.

The ratio of volumes of CH₃COOH 0.1 N to CH₃COONa 0.1 N required to prepare a buffer solution of pH 5.74 is (Given, pK_a of CH₃COOH is 4.74)

10 : 1
5 : 1
1 : 5
1 : 10

44.

Within the list shown below, the correct pair of structures of alanine in pH ranges 2-4 and 9-11 is

I. H₃N⁺- CH(CH₃)CO₂H

II. H₂N - CH(CH₃)CO $_{2}^{-}$

III. H₃N⁺-CH(CH₃)CO $_{2}^{-}$

IV. H₂N-CH(CH₃)CO₂H

I and II
I and III
II and III
III and IV

45.

The correct statement regarding the following energy diagrams is

Reaction M is faster and less exothermic than reaction N
Reaction M is slower and less exothermic than reaction N
Reaction M is faster and more exothermic than reaction N
Reaction M is slower and more exothermic than reaction N

46.

At 25°C, the solubility product of salt of MX₂ type is 3.2 × 10^-8 in water. The solubility (in mol/L) of MX₂ in water at the same temperature will be