Answer
General guidance
Bond order represents the number of bonds present in between two bonded atoms. It also explains the stability of a bond.
Molecular orbital diagram:
For the diatomic molecules like hydrogen and helium, the following molecular orbital diagram is used.
First, the electrons fill the bonding molecular orbital and then move to anti – bonding molecular orbital. If the electrons in molecular orbitals are paired, then it is called as diamagnetic. If the electrons in molecular orbitals are unpaired, then it is called as paramagnetic.
Bond order can be calculated by:
Step-by-step
Step 1 of 2
Each hydrogen atom contains 1 electron. First, both electrons fill the lower energy level 
and there is no electron in anti – bonding orbitals.
Step 2 of 2
Bond order cannot be zero. It is because, there are 2 electrons present in bonding molecular orbital.
There are 2 electrons present in bonding molecular orbital. Therefore, the bond order cannot be 0.5.
Bond order cannot be 1.5. It is because, there are 2 electrons in bonding molecular orbital and there are no electrons in anti – bonding molecular orbital.
Bond order cannot be 2. It is because, there are 2 electrons in bonding molecular orbital and there are no electrons in anti – bonding molecular orbital.
The number of electrons in bonding molecular orbital is 2 and there is no electron in anti – bonding molecular orbital. By substituting the above values using bond order formula, it gives the bond order as 1.
Molecular orbital diagram of hydrogen
molecule:
Bond order:
From the molecular orbital diagram, there are 2 electrons in bonding molecular orbital and there is no anti – bonding molecular orbital. The bond order can be determined by substituting those values using bond order formula.
Answer
Molecular orbital diagram of hydrogenmolecule:
Bond order:
Answer only
Molecular orbital diagram of hydrogenmolecule:
Bond order: