# The freezing point of an aqueous solution of KCN containing 0.1892 mol $kg^{–1}$ was found to be $-0.704^{\large\circ}$C. On adding 0.095 mol of $Hg(CN)_2$, the freezing point of the solution was found to be $-0.530^{\large\circ}$C. If the complex – formation takes place according to the following equation $Hg(CN)_2+nKCN\leftrightharpoons K_n[Hg(CN)_{n+2}]$.What is the formula of the complex ?.$K_r(H_2O)$ is $1.86kgmol^{-1}K$

$K_2[Hg(CN)_4]$