P-Block elements group-15,16,17,18

The elements of group 1,2,13,14,15,16,17,18 are collectively called

Radioactive element of group 17 is

Arrange the following elements in the descending order of atomic size and give a reason for your answer. Mg, Cl, P, Ar (Atomic numbers of the above elements are 12, 17, 15, 18 respectively).

The elements of group 18 are called

Name the radioactive element of group 17 ________ and group 18 _____________.

The first ionization energies of the lighter elements of group 16 are ________ those of group 15 elements.