Which of the following diatomic molecular species has only a bonds according to Molecular Orbital Theory ?

Question : Which of the following diatomic molecular species has only a bonds according to Molecular Orbital Theory ?

(1) O₂

(2) N₂

(3) C₂ 

(4) Be₂

Answer : from all above options the correct answer is “(3) C₂ ” after viewing all options we can say that According to molecular orbital, only C₂ has π bonds.

to make it clear please see the equation given below –

Answer explanation : first of all you must know that according to Molecular Orbital Theory “all the atoms has tendency to combine together and crate molecular orbitals ” from this theory if we calculate than we found bond order of 2 in O₂ , 3 in N₂ , zero in Be₂ , and C2​ molecule has 1 $\sigma$ aid 1 $\pi$ bond , that is why we have marked option ((3) C₂ ) for correct answer as per question requirement.