Question

Which of the following has the least atomic radius?

• A. B
• B. C
• C. N
• D. O
• E. F

Hint:

Atomic radius decreases across a period due to the increasing effective nuclear charge pulling electrons closer to the nucleus.

Answer 1

Answer: (E)

As we move across a period in the periodic table from left to right, the atomic radius decreases due to an increase in effective nuclear charge. Among the elements B, C, N, O, and F, fluorine (F) has the smallest atomic radius because it is furthest to the right in the second period. 
Thus, the correct answer is (E).