Explain the variations in electron gain enthalpy and electronegativity of group-$16$ elements.

(N/A) $(i)$ Electron gain enthalpy: Group-$16$ elements have high negative electron gain enthalpy. Oxygen has a less negative electron gain enthalpy than sulphur due to the compact nature (small size) of the oxygen atom,which leads to inter-electronic repulsions. From sulphur onwards,the electron gain enthalpy becomes less negative down the group up to polonium.
Order of electron gain enthalpy: $O < S > Se > Te > Po$
$(ii)$ Electronegativity: Oxygen is the second most electronegative element after fluorine. Down the group,electronegativity decreases with an increase in atomic number. This implies that metallic character increases from oxygen to polonium.