The correct order of the metallic character of the elements $$\mathrm{Be}, \mathrm{Al}, \mathrm{Na}, \mathrm{K}$$ is

Which of the following tetrahalides does not exist?

The element with outer electronic configuration $$(n-1) d^2 n s^2$$, where $$n=4$$, would belong to

Choose the correct option regarding the following statements

Statement 1 Nitrogen has lesser electron gain enthalpy than oxygen.

Statement 2 Oxygen has lesser ionisation enthalpy than nitrogen.