Correct option (a) Both A and R are true and R is the correct explanation of A
Explanation:
Bond order of N= 3, bond order of O2 =2.
Higher the bond order, higher is the bond dissociation energy. z.e, higher stability or less reactivity.
Thus, N2 is less reactive than O2.
Higher the bond order, shorter is the bond length. Shorter bond length of N2 shows its higher bond order.