Question

The bond order in $N_2^+$ is
(a) 1.5
(b) 3.0
(c) 2.5
(d) 2.0

Answer 1

The given question is based on Molecular Orbital Theory.
Bond order = 1/2*(No.of electrons in Bonding Molecular Orbitals - No.of electrons I Antibonding molecular Orbitals)
Now,
this is one method by which you can approach the question.
However, another idea is by knowing the no of total electrons the molecular has we can directly tell it's bond order.
This table is as follows,
Just remember that N2 that is 14 electrons has a bond order of 3
Now, everytime you increase or decrease an electron , the bond order decreases by 0.5
So,
For example for the given molecule
N2+ , the no of electrons are 13. So, the bond order will be (3-0.5) = 2.5

Another example, N2- Here there are 15 electron
So,
it's bond order would also be 2.5
Another example, O2 which has 16 electrons
So, it's bond order would be (3-2*0.5) = 3-1 = 2

Hope this helps you !
If you've any doubts , please ask me in the comment section and I'll try to clarify !