If C - C (I), C = C(II) and C ≡ C(III) are three bond types, then their bond order will be respectively,
1, 2, 3
Generally, we can state that number of bonds = Bond order. This is not always the case but happens to be a quick rule of approximation.
Here, C−C⇒Bond Order=1
C=C⇒Bond Order=2
C≡C⇒Bond Order=3
Also, Bond Order∝1Bond Length
Bond Order∝Bond Enthalpy