(a, c, d)

They readily form cations by losing valence shell electron on account of their bigger atomic sizes.

They readily form cations by losing valence shell electron because of low ionization energies on account of their bigger atomic sizes. Hence they have high oxidation potentials.

Metallic bonds are weaker because of bigger atomic size and one valence electron per atoms. Hence they have low melting point due to weak metallic bonds.

They readily dissolve in liquid ammonia at –33ºC (boiling point of ammonia) forming blue colour solutions.

M + (x + y) NH3 [M(NH3)x]+ + [e(NH3)y]–