The first element of a group differs in many ways from the other heavier members of the group due to:

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) ($1 \ eV = 1.6 \times 10^{-19} \ J$,$N_A = 6.022 \times 10^{23} \ mol^{-1}$)

Which group is called the buffer group of the periodic table?

Choose the incorrect order.

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

Which of the following order$(s)$ is/are correct?
$(1) Li < Be < B < C$ $(IE_1)$
$(2) Li < Na < K < Rb < Cs$ (Reducing power in gaseous state)
$(3) Li^{+} < Na^{+} < K^{+} < Rb^{+} < Cs^{+}$ (Ionic mobility in aqueous solution)
$(4) S > Se > Te > O$ $(EA)$