An inorganic compound gives off $${O_2}$$  when heated, turns an acidic solution of $$KI$$  violet and reduces acidified $$KMn{O_4}.$$  The compound is

Solution :
\[\begin{align} & \text{2}{{\text{H}}_{2}}{{O}_{2}}\xrightarrow{\Delta }2{{H}_{2}}O+{{O}_{2}} \\ & 2KI+{{H}_{2}}{{O}_{2}}\to 2KOH+{{I}_{2}} \\ & 2KMn{{O}_{4}}+3{{H}_{2}}S{{O}_{4}}+5{{H}_{2}}{{O}_{2}}\to {{K}_{2}}S{{O}_{4}}+2MnS{{O}_{4}}+8{{H}_{2}}O+5{{O}_{2}} \\ \end{align}\]