Question

Compare the radii of two species X and Y.
(a) X has 12 protons and 12 electrons.
(b) Y has 12 protons and 10 electrons.

• A. Radii of Y is more than X
• B. Radii of Y is less than X
• C. Both have equal radii
• D. None of these

Answer 1

Answer: (B)

Radii of Y is less than X

As both X and Y had 12 protons both has atomic number 12 that is magnesium. In case of Y, we have only 10 electrons because of this the affect of nuclear charge on the electrons is more than that of on 12 electrons(happens for same number of protons). Hence, radii of Y is smaller than that of X.