Question

Which of the following has smallest radius?

• A. $1s^2,2s^{2}2p^6,3s^2$
• B. $1s^2,2s^{2}2p^6,3s^{2}3p^1$
• C. $1s^2,2s^{2}2p^6,3s^{2}3p^5$
• D. $1s^2,2s^{2}2p^6,3s^{2}3p^3$

Answer 1

Answer: (C)

All the elements are of the same periods because all have the equal number of shell. In a period, the size of atom decreases as we from left to right i.e. from $A$ to $B$ to $D$ to $C$. Hence, element corresponding to C is smallest in the size. Halogen is the smallest atom in a given period of periodic table.