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 :
$$O < S < Se < As$$
Solution :
On moving down in a group atomic radii 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., $$O < S < Se < As$$
Releted MCQ Question on Inorganic Chemistry >> Classification of Elements and Periodicity in Properties
Releted Question 1
The correct order of second ionisation potential of carbon, nitrogen, oxygen and fluorine is