$\mathrm{MnO}_3$ in an acidic medium dissociates into

• Correct answer
  A

  $\mathrm{MnO}_2$ and $\mathrm{MnO}_4^{-}$
• B

  $\mathrm{MnO}$ and $\mathrm{MnO}_4^{-}$
• C

  $\mathrm{MnO}_2$ and $\mathrm{MnO}$
• D

  $\mathrm{MnO}_2$ and $\mathrm{MnO}_3$

Solution

In acidic solution, manganese (VI) becomes unstable and undergo disproportionation to form manganese (VII) and manganese (IV)

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