The depression in freezing point observed for a formic acid solution of concentration $$0.5 \mathrm{~mL} \mathrm{~L}^{-1}$$ is $$0.0405^{\circ} \mathrm{C}$$. Density of formic acid is $$1.05 \mathrm{~g} \mathrm{~mL}^{-1}$$. The Van't Hoff factor of the formic acid solution is nearly : (Given for water $$\mathrm{k}_{\mathrm{f}}=1.86\, \mathrm{k} \,\mathrm{kg}\,\mathrm{mol}^{-1}$$ )

For a solution of the gases A, B, C and D in water at 298 K, the values of Henry's law constant (K_H) are 30.40, 2.34, 1.56 $$\times$$ 10^$$-$$5 and 0.513 k bar respectively. In the given graph, the lines marked as 'p' and 's' correspond respectively to :

Given below are two statements : one is labelled as Assertion (A) and the other is labelled as Reason (R).

Assertion (A) : At 10$$^\circ$$C, the density of a 5 M solution of KCl [atomic masses of K & Cl are 39 & 35.5 g mol^$$-$$1 respectively], is 'x' g ml^$$-$$1. The solution is cooled to $$-$$21$$^\circ$$C. The molality of the solution will remain unchanged.

Reason (R) : The molality of a solution does not change with temperature as mass remains unaffected with temperature.

In the light of the above statements, choose the correct answer from the options given below :

Solute A associates in water. When 0.7 g of solute A is dissolved in 42.0 g of water, it depresses the freezing point by 0.2$$^\circ$$C. The percentage association of solute A in water, is :

[Given : Molar mass of A = 93 g mol^$$-$$1. Molal depression constant of water is 1.86 K kg mol^$$-$$1.]