A violet compound of manganese (A) decomposes on heating to liberate oxygen and compounds (B) and (C) of manganese are formed. Compound (C) reacts with KOH in the presence of potassium nitrate to give compound (B). On heating compound (C) with conc. H2SO4 and NaCl, chlorine gas is liberated and a compound (D) of manganese along with other products is formed. Identify compounds A to D and also explain the reactions involved.

Thinking Process

This problem is based on preparation and properties of KMnO4 , K2MnO4 and MnO2

NEETprep Answer: Since, compound (C) on treating with conc. H2SO4 and NaCl  gives Cl2 gas, so it is manganese dioxide (MnO2) . It is obtained along with   MnO42- when  KMnO4 (violet) is heated.
 Thus, (A) = KMnO4                         (B) = K2MnO4
           (C) = MnO2                            (D) = MnCl2

  KMnO4  K2MnO4 + MnO2 + O2
     A                  B            C

2MnO2 + 4KOH + O2  2K2MnO4 + 2H2O

MnO2 + 4NaCL + 4H2SO4  MnCL2 + 4NaHSO4 + 2H2O + CL2