Question

The order of increasing sizes of atomic radii among the elements O, S, Se and As is :

• A. As < S < O < Se
• B. Se < S < As < O
• C. O < S < As < Se
• D. O < S < Se < As

Answer 1

Answer: (D)

On moving down in a group atomic radius increases due to successive addition of extra shell hence
O < S < Se
Further As is in group 15 having one less electron in its p orbital hence have higher atomic radii than group 16 elements.
i.e., O < S < Se < As