Q55. Considering acetic acid dissociates in water, its dissociation constant is $6.25 \times 10 ^ { - 5 }$. If 5 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 $0 ^ { \circ } \mathrm { C } . x =$
$$\begin{aligned}
& \left( \mathrm { K } _ { f } \right) _ { \text {water } } = 1.86 \mathrm {~K} \mathrm {~kg} \mathrm {~mol} ^ { - 1 } . \\
& \text { density of acetic acid is } 1.2 \mathrm {~g} \mathrm {~mol} ^ { - 1 } .
\end{aligned}$$
$\_\_\_\_$ . (Nearest integer) Given : molar mass of water $= 18 \mathrm {~g} \mathrm {~mol} ^ { - 1 }$. Acetic acid dissociates as molar mass of acetic acid $= 60 \mathrm { gmol } ^ { - 1 }$.
$$\text { density of water } = 1 \mathrm {~g} \mathrm {~cm} ^ { - 3 }$$
$\mathrm { CH } _ { 3 } \mathrm { COOH } \rightleftharpoons \mathrm { CH } _ { 3 } \mathrm { COO } ^ { \ominus } + \mathrm { H } ^ { \oplus }$\\