Which of the following sets of solutions of urea ( mol . mass $60 \mathrm{~g} \mathrm{~mol}^{-1}$ ) and sucrose ( mol . mass $342 \mathrm{~g} \mathrm{~mol}^{-1}$ ) is isotonic?

Which of the following sets of components form homogeneous mixture?

Calculate van't Hoff-factor for 0.2 m aqueous solution of KCl which freezes at $-0.680^{\circ} \mathrm{C}$. $\left(K_f=1.86 \mathrm{~K} \mathrm{~kg} \mathrm{~mol}^{-1}\right)$

' $K$ is Henry's constant and has the unit