Question

Arrange the following elements in the decreasing order of their atomic radius: oxygen, carbon, lithium.

Answer 1

Atomic radius is the distance between the nucleus of the atom and its outermost shell.
Lithium, carbon and oxygen are present in same period of the periodic table. As we move from left to right across any period, the atomic radii decreases as the effective nuclear charge increases.
So the correct order is:
Lithium > carbon > oxygen