Considering acetic acid dissociates in water, its dissociation constant is $6.25 \times 10^{-5}$. If $5 \mathrm{~mL}$ of acetic acid is dissolved in 1 litre water, the solution will freeze at $-x \times 10^{-2}{ }^{\circ} \mathrm{C}$, provided pure water freezes at $0{ }^{\circ} \mathrm{C}$. $x=$$\underline{\hspace{2cm}}$. (Nearest integer) $$\begin{aligned} \text{Given :} \quad & \left(\mathrm{K}_{\mathrm{f}}\right)_{\text {water }}=1.86 \mathrm{~K} \mathrm{~kg} \mathrm{~mol}-1 \\ & \text { density of acetic acid is } 1.2 \mathrm{~g} \mathrm{~mol}^{-1} \text {. } \\ & \text { molar mass of water }=18 \mathrm{~g} \mathrm{~mol}^{-1} \text {. } \\ & \text { molar mass of acetic acid= } 60 \mathrm{~g} \mathrm{~mol}^{-1} \text {. } \\ & \text { density of water }=1 \mathrm{~g} \mathrm{~cm}^{-3} \end{aligned}$$ Acetic acid dissociates as $$\mathrm{CH}_3 \mathrm{COOH} \rightleftharpoons \mathrm{CH}_3 \mathrm{COO}^{\ominus}+\mathrm{H}^{\oplus}$$