A $0.5$ percent solution of potassium chloride was found to freeze at $-0.24 °\mathrm{C}$. The percentage dissociation of potassium chloride is (Nearest integer)
(Molal depression constant for water is $1.80 \mathrm{K} \mathrm{kg}{ \mathrm{mol}}^{-1}$ and molar mass of $\mathrm{KCl}$ is $74.6 \mathrm{g}{ \mathrm{mol}}^{-1}$)

Given below are two statements : one is labelled as Assertion and the other is labelled as Reason.

Assertion: At $10 °\mathrm{C}$, the density of a $5 \mathrm{M}$ solution of $\mathrm{KCl}$ [atomic masses of $\mathrm{K} \& \mathrm{Cl}$ are $39 \& 35.5 \mathrm{g}{ \mathrm{mol}}^{-1}$ respectively], is '$\mathrm{x}$' ${\mathrm{gml}}^{-1}$. The solution is cooled to $-21 °\mathrm{C}$. The molality of the solution will remain unchanged.

Reason: The molality of a solution does not change with temperature as mass remains unaffected with temperature.

In the light of the above statements, choose the correct answer from the options given below.

$2.5 \mathrm{g}$ of protein containing only glycine $\left({\mathrm{C}}_2{\mathrm{H}}_5{\mathrm{NO}}_2\right)$ is dissolved in water to make $500 \mathrm{mL}$ of solution. The osmotic pressure of this solution at $300 \mathrm{K}$ is found to be $5.03\times {10}^{-3}$ bar. The total number of glycine units present in the protein is

(Given : $\mathrm{R} = 0.083 \mathrm{L} \mathrm{bar} {\mathrm{K}}^{-1} {\mathrm{mol}}^{-1} )$