A 'p'-block element $(\mathrm{E})$ and hydrogen form a binary cation $\left(\mathrm{EH}_{\mathrm{x}}\right)^{+}$, while $\mathrm{EH}_3$ on treatment with $\mathrm{K}_2 \mathrm{HgI}_4$ in alkaline medium gives a precipitate of basic mercury(II)amido-iodine. Given below are first ionisation enthalpy values $\left(\mathrm{kJmol}^{-1}\right)$ for first element each from group $13,14,15$ and 16 . Identify the correct first ionisation enthalpy value for element E .