Question

Arrange the following elements in increasing order of first ionization enthalpy:
Li, Be, B, C, N
Choose the correct answer from the options given below:

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

Answer 1

Answer: (B)

Li < B < Be < C < N

Answer 2

1. Ionization enthalpy increases across a period due to increased nuclear charge.

2. The anomaly: B $<$ Be because Be has a fully filled $2s^2$ configuration, making it more stable.

3. Final order: Li $<$ B $<$ Be $<$ C $<$ N.