Question

Which one of the following has the smallest size ?

• A. $Al$
• B. $A{l}^{+}$
• C. $A{l}^{2+}$
• D. $A{l}^{3+}$

Answer 1

The correct option is D $A{l}^{3+}$

An atom after losing an electron forms a cation and since the net charge on the atom increases the atomic size increases. The greater the charge on the atom smaller the size of the ion so $Al\left(III\right)$ cation is smallest in size.