Question

Rank elements Li, Be, B, C in increasing first ionization energy:

• A. Li<B<C<Be
• B. Li<C<B<Be
• C. Be<C<B<Li
• D. Li<Be<B<C

Hint:

The first ionization energy generally increases across a period from left to right.

Answer 1

The Correct Option is D

Moving left to right across period 2, nuclear charge increases while the shielding from inner electrons stays about the same, so it generally gets progressively harder to remove an outer electron. Applying that straightforward trend across lithium, beryllium, boron, and carbon in order gives a steadily increasing sequence, which is option (D).