Which one of the following sets of ions represents a collection of isoelectronic species?

Which one of the following sets of ions represents the collection of isoelectronic species?

The ionisation enthalpies of elements of the second period are given below: Ionisation enthalpy / $kcal \, mol^{-1}$: $520, 899, 801, 1086, 1402, 1314, 1681, 2080$. Match the correct enthalpy with the elements and complete the graph given in Fig. Also,write the symbols of the elements with their atomic numbers.

Which of the following statement$(s)$ is/are correct?

The first ionization energy for $Li$ is $5.4 \ eV$ and electron affinity of $Cl$ is $3.61 \ eV$. The $\Delta H$ (in $kJ/mol$) for the reaction $Li_{(g)} + Cl_{(g)} \to Li^{+}_{(g)} + Cl^{-}_{(g)}$ is (if resulting ions do not combine with each other) ($1 \ eV = 1.6 \times 10^{-19} \ J$,$N_A = 6.022 \times 10^{23} \ mol^{-1}$)

Point out the wrong statement: On moving horizontally from left to right across a period in the periodic table