Question

The correct order in which the first ionization enthalpy increases is

• A. K, Be, Na
• B. Be, Na, K,
• C. Na, K, Be
• D. K, Na, Be

Answer 1

The correct option is D

K, Na, Be

The I.E of Be $\left(2s^2\right)$ is maximum because electron is to be drawn from stable orbital. The $I{E}_1$ of Na $\left(3s^1\right)$ is greater than K $\left(4s^1\right)$ because size of K is bigger than Na.