Compare the radii of two species X and Y. Give reasons for your answer.
(a) X has 12 protons and 12 electrons
(b) Y has 12 protons and 10 electrons.

Explanation

Since species X has 12 protons and 12 electron, it is electrically neutral. Since, species Y has 12 protons and 10 electrons, therefore, it has two units positive charge. The electronic configuration of the two species are
`{:("Species X "," Species Y"),("K L M"," K L"),("2 8 2"," 2 8"):}`
Since, species X has three shells while species Y has two shells, therefore, species Y has smaller radius than species X.