Which of the following statements is false ?

• A

  $\mathrm{CaOCl}_2$ gives $\mathrm{OH}^{-}, \mathrm{Cl}^{-}$and $\mathrm{OCl}^{-}$in aqueous solution
• B

  Diamond and graphite are allotropes of carbon
• Correct answer
  C

  Bleaching action of $\mathrm{Cl}_2$ in moist condition is not permanent
• D

  Calomel is $\mathrm{Hg}_2 \mathrm{Cl}_2$

Hence, the correct answer is option: 'C'.