(a) Down the group, the atomic size increases with increasing atomic number and so attraction for shared pair of electrons decreases. Hence electronegativity decreases
(b) Down the group, the atomic size increases with increasing atomic number and so attraction between valence electron and nucleus decreases. Hence ionization energy decreases
(c) Down the group atomic size increases with increase in number of atomic shells while effective nuclear charge remains constant
(d) Down the group atomic size increases with increase in number of atomic shells and therefore, the strength of metallic bond decreases. So melting point decreases