AP EAPCET 18 May 2024 Shift 1 Solved Paper

The correct match is A-II, B-IV, C-I, D-III.Electron gain enthalpy is the energy released when an electron is added to an isolated gaseous atom, so the values are negative.The accepted values are:$\; \mathrm{F} \longrightarrow -328\ \mathrm{kJ\,mol}^{-1}$$\; \mathrm{Cl} \longrightarrow -349\ \mathrm{kJ\,mol}^{-1}$$\; \mathrm{O} \longrightarrow -141\ \mathrm{kJ\,mol}^{-1}$$\; \mathrm{S} \longrightarrow -200\ \mathrm{kJ\,mol}^{-1}$The magnitude becomes more negative on moving left to right across a period, since nuclear charge increases and atomic size decreases.Hence $\mathrm{Cl}$ has the most negative value and $\mathrm{O}$ has the least negative value among the four.However, $\mathrm{F}$ is unexpectedly less negative than $\mathrm{Cl}$ because of the very small size of the $2p$ orbital, which causes strong inter-electronic repulsion and a high electron density in the compact shell.Similarly, $\mathrm{S}$ is more negative than $\mathrm{O}$ because the larger $3p$ orbital of $\mathrm{S}$ accommodates the incoming electron with less repulsion.So the matching is $\mathrm{A-II}$, $\mathrm{B-IV}$, $\mathrm{C-I}$, $\mathrm{D-III}$, i.e. option A-II, B-IV, C-I, D-III.