2 g of benzoic acid (C₆H₅COOH) dissolved in 25 g of benzene shows a depression in freezing point equal to 1.62 K. Molal depression constant for benzene is 4.9 K kg mol^–1. The percentage association of acid if it forms dimer in solution is-

1. 98.5%
2. 99.2 %
3. 97.5 %
4. 95.2 %

0.6 mL of acetic acid (CH₃COOH), having density 1.06 g mL^–1, is dissolved in 1 litre of water. The depression in freezing point observed for this strength of acid was 0.0205°C. The value of van’t Hoff factor and the dissociation constant of acid are respectively -

1. 1.041; 1.86 × 10^–5
2. 2.073; 1.86 × 10^–5
3. 0.091; 1.76 × 10^–5
4. 1.041; 1.76 × 10^–5