The C𝑙 − O  bond order in per chlorate ion ${\mathrm{ClO}}_4^{-}$

The structure of per chlorate ion is shown below:

The bond order in C𝑙 − O is

Bond Order$=\frac{\mathrm{Tatal} \mathrm{no}.\mathrm{of} \mathrm{Bonds}}{\mathrm{No}. \mathrm{of} \mathrm{Oxygen} \mathrm{atoms}}$

$=\frac{7}{4}=1.75$