The increasing order of electron affinity for the following electronic configurations of element
$$\begin{gathered} \text{ (I) }1{\mathrm{s}}^{2}2{\mathrm{s}}^{2}2{\mathrm{p}}^{6}3{\mathrm{s}}^{2}3{\mathrm{p}}^5 \\ \text{ (II) }1{\mathrm{s}}^{2}2{\mathrm{s}}^{2}2{\mathrm{p}}^3 \\ \text{ (III) }1{\mathrm{s}}^{2}2{\mathrm{s}}^{2}2{\mathrm{p}}^5 \\ \text{ (IV) }1{\mathrm{s}}^{2}2{\mathrm{s}}^{2}2{\mathrm{p}}^{6}3{\mathrm{s}}^1 \end{gathered}$$

The affinity of electron depends on the outer shell configuration of an element.
From given configurations, III will have highest electron affinity as 2p is more closer to the nucleus and it is deficient of 1 electron to complete its octet. This will be followed by IV where 3s orbital requires 1 electron. II will have less electron affinity than IV because half-filled p orbital is stable. I will have the least electron affinity as 3p is comparatively farther from nucleus. Hence, the required order is:
III>IV>II>I