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.]

The K_sp for bismuth sulphide (Bi₂S₃) is 1.08 $$\times$$ 10^$$-$$73. The solubility of Bi₂S₃ in mol L^$$-$$1 at 298 K is :

The correct order of electron gain enthalpies of Cl, F, Te and Po is

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

Assertion A : The amphoteric nature of water is explained by using Lewis acid/base concept.

Reason R : Water acts as an acid with NH₃ and as a base with H₂S.

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