(a) (i) Henry's Law: It states the partial vapour pressure of gas in vapour phase is directly proportional to mole fraction of the gas in the solution.
p = K_H.x
where K_H is Henry's law constant, 'x' is mole fraction of gas in solution and p is partial vapour pressure of the gas in solution.
(ii) Raoult's Law for solution of non-volatile solute: The relative lowering of vapour pressure for a solution is equal to the mole fraction of solute when solvent alone is volatile.
\({p_A^0-p_A\over p_A^0}=x_B\)
where p⁰ is vapour pressure of pure component 'A', p_A is vapour pressure of component 'A' in solution, x_B is mole fraction of solute, P_A⁰ - P_A is lowering of vapour pressure and \(p_A^0-p_A\over p_A^0\) is relative lowering of vapour pressure.
(b) πV = nRT
\(\Rightarrow\ \pi V={W_B\over M_B}\times R \times T\)
\(\Rightarrow\ {0.335\over 760}\times{35\over 1000}={8.95\times10^{-3}\times0.0821\times 2988\over M_B}\)
\(\Rightarrow\ M_B={760 \times 1000 \times 8.95 \times 10-3 \times 0.0821\times 298\over 0.335\times35}\)
\(={166.416\times10^3\over11.725}=14.19\times10^3\)
= 1.419 x 10⁴ g mol^-1

(i) Dispersion forces
(ii) Dispersion forces
(iii) Ion-dipole attraction
(iv) H-bound and dipole-dipole attraction
(v) Dipole -dipole attraction.

(b) If x_A is mol fraction of A in liquid phase, then x_A (450)+(1 - x_A)(700) = 600 or x_A = 0.4, x_B = 0.6.
Hence, \({ p }_{ A }=0.4\times 450=180\quad mm,{ p }_{ B }=0.6\times 700=420\quad mm,{ y }_{ A }=\frac { 180 }{ 600 } =0.3,{ y }_{ B }=\frac { 420 }{ 600 } =0.7\)