The osmotic pressure of a dilute solution of an ionic compound XY in water is four times that of a solution of 0.01 M BaCl₂ in water. Assuming complete dissociation of the given ionic compounds in water, the concentration of XY (in mol L^–1) in solution is :

Among the following, the set of parameters that represents path function, is :
(A) q + w
(B) q
(C) w
(D) H–TS

The standard Gibbs energy for the given cell reaction in kJ mol^–1 at 298 K is :

Zn(s) + Cu²⁺ (aq) $$ \to $$ Zn²⁺ (aq) + Cu (s),

E° = 2 V at 298 K

(Faraday's constant, F = 96000 C mol^–1)

Consider the van der Waals constants, a and b, for the following gases.

Gas	Ar	Ne	Kr	Xe
a/ (atm dm6 mol–2)	1.3	0.2	5.1	4.1
b/ (10–2 dm3 mol–1)	3.2	1.7	1.0	5.0

Which gas is expected to have the highest critical temperature?