Which of the statements given below is incorrect

• A

  ${\mathrm{Cl}}_2{\mathrm{O}}_7$ is  an anhydride of perchloric acid 

• B

  ${\mathrm{O}}_3$ molecule is bent 

• C

  ONF is isoelectronic with  ${\mathrm{O}}_2{\mathrm{N}}^{-}$

• D

  $O{F}_2\text{ is }$ an oxide of fluorine