When 0.25 moles of a non-volatile, non-ionizable solute was dissolved in 1 mole of a solvent the vapor pressure of solution was $x \%$ of vapor pressure of pure solvent. What is $x \%$ ?

At $27^{\circ} \mathrm{C}, 0.1 \mathrm{M}, 1 \mathrm{~L} \mathrm{~K}_4\left[\mathrm{Fe}(\mathrm{CN})_6\right]$ aqueous solution and $0.1 \mathrm{M}, 1 \mathrm{~L} \mathrm{FeCl}_3$ aqueous solution are placed in a container separated by a semi permeable membrane AB . Assume complete dissociation of both the solutes. Which of the following statement is correct?

Solution A is prepared by dissolving 1 g of a protein (molar mass = 50,000 g mol^-1) in 0.5 L of water at 300 K. Its osmotic pressure is $x$ bar. Solution B is made by dissolving 2 g of the same protein in 1 L of water at 300 K. Osmotic pressure of solution B is $y$ bar. Entire solution of A is mixed with entire solution of B at the same temperature. The osmotic pressure of resultant solution is $z$ bar. $x$, $y$ and $z$ respectively are:
(R = 0.083 L bar mol^-1 K^-1)

19.5 g of fluoro acetic acid (molar mass = 78 g mol⁻¹) is dissolved in 500 g of water at 298 K. The depression in the freezing point of water was 1^∘C. What is $K_a$ of fluoro acetic acid?

(For water, $K_f = 1.86$ K kg mol⁻¹). Assume molarity and molality to have same values.