The correct statement with respect to dinitrogen is :

Solution

Chemistry ma’am · 2 steps

Everything about N₂ comes back to one strong triple bond, so test each option against it.

1. The triple bond. In N≡N the bond enthalpy is about 946 kJ mol⁻¹, one of the strongest bonds known. That makes dinitrogen very unreactive at room temperature.

   Option	What is true	Verdict
   (a) paramagnetic	All 10 valence electrons are paired, σ 1s² and so on up to σ 2p_z², bond order 3	diamagnetic, false
   (b) inert diluent	Its inertness lets it blanket or dilute reactive chemicals without reacting	true
   (c) reacts with O₂ at 25 °C	N₂ + O₂ ⇌ 2NO needs very high temperature, about 2000 K or an electric arc	false
   (d) not used in cryosurgery	Liquid N₂ boils at 77 K and is used to freeze and destroy tissue	false

2. So. Only (b) is correct: dinitrogen is used as an inert diluent and as an inert atmosphere for reactive chemicals.

The idea to keep. Dinitrogen is inert because of its very strong triple bond, and it is diamagnetic because every electron is paired. Its uses, like inert atmospheres and liquid N₂ as a coolant, come from these two facts.

Answer from the NTA final answer key. Solution by PrepWiser.