Calculate osmotic pressure of a solutions having $0.1\; M\;NaCl$ and $0.2\; M\; Na_2SO_4$ and $0.5 M\; HA$. (Given: Weak acid is 20% dissociated at $300^{\circ}K$)

Question

$\begin{array}{1 1} 34.482\;atm \\ 16.872\;atm \\ 24.694\;atm \\ 36.762\;atm \end{array}$