The successive 5 ionisation energies of an element are 800,2427,3658,25024 and 32824 kJ/mol, respectively. $\begin{aligned}
& \frac{\mathrm{IE}_2}{\mathrm{IE}_1}=\frac{2427}{800}=3.03 \
& \frac{\mathrm{IE}}{\mathrm{IE}_2}=\frac{3658}{2427}=1.51 \
& \frac{\mathrm{IE}}{\mathrm{IE}_3}=\frac{25024}{3658}=6.84
\end{aligned}\frac{\mathrm{IE}_5}{\mathrm{IE}_4}=\frac{32824}{25024}=1.31Since(\mathrm{IE}_4 / \mathrm{IE}_3$ ) value is maximum, the element belongs to group 13.