Electromagnetic radiation of wavelength 663 nm is just sufficient to ionise the atom of metal A . The ionization energy of metal $A$ in $\mathrm{kJ} \mathrm{mol}^{-1}$ is
$\_\_\_\_$ (Rounded-off to the nearest integer)
$$
\begin{aligned}
& {\left[\mathrm{h}=6.63 \times 10^{-34} \mathrm{Js}, \mathrm{c}=3.00 \times 10^8 \mathrm{~ms}^{-1}\right.} \\
& \left.\mathrm{N}_{\mathrm{A}}=6.02 \times 10^{23} \mathrm{~mol}^{-1}\right]
\end{aligned}
$$