question_answer

The compound (A) , (B) and (C) are

A) A - \[Mn{{O}_{2}}\]                B - \[{{K}_{2}}Mn{{O}_{4}}\]            C - \[KMn{{O}_{4}}\]

B) A - \[M{{n}_{2}}{{O}_{3}}\]               B - \[Mn{{O}_{2}}\]                C - \[{{K}_{2}}Mn{{O}_{4}}\]

C) A - \[{{K}_{2}}Mn{{O}_{4}}\]            B - \[KMn{{O}_{4}}\]              C - \[M{{n}_{2}}{{O}_{3}}\]

D) A - \[KMn{{O}_{4}}\]             B - \[M{{n}_{2}}{{O}_{3}}\]              C - \[Mn{{O}_{2}}\]

Correct Answer: A

Solution :

[a] The reaction is a preparation of \[KMn{{O}_{4}}\] from the pyrolusite ore, \[Mn{{O}_{2}}\] (blackish brown) (i) \[2Mn{{O}_{2}}+4KOH+{{O}_{2}}/\] or oxidizing agent \[KN{{O}_{3}}\] [a]             (ii) \[{{K}_{2}}Mn{{O}_{4}}\] disproportionates in a neutral or acidic solution to give \[KMn{{O}_{4}}\]