Does chlorine or silicone have a smaller atomic radius and why

Chlorine.

Explanation:

Since chlorine's 17 protons are greater than magnesium's 12 protons, chlorine will have a greater effective nuclear charge to draw chlorine's valence electrons closer to the nucleus and, thus, chlorine is expected to have the smaller atomic radius, while magnesium with the lower effective nuclear charge is expected to have a smaller amount of radius.

the answer is c. nacl