Given below are two statements. One is labelled as Assertion A and the other is labelled as Reason R . Assertion A : The first ionization enthalpy for oxygen is lower than that of nitrogen. Reason R : The four electrons in 2 p orbitals of oxygen experience more electron-electron repulsion. In the light of the above statements, choose the correct answer from the options given below.

Step-by-step solution

Ionization energy of oxygen is less than that of nitrogen because 2 p subshell of nitrogen is half filled, and half filled orbitals have some extra stability, so removing electrons from them will be little more difficult. And In oxygen atom, 2 of the four 2 p electrons must occupy the same 2 p orbital resulting in an increased electron electron-repulsion. N = 1 s 2 2 s 2 2 p 3 O = 1 s 2 2 s 2 2 p 4