When a chromateore (A) is fused with sodium carbonate in free excess of air and the product is dissolvedin water, a yellow solution of compound (B)) is obtained. After treatment of this yellow solution with sulphuricacid, compound (C ) can be crystallisedfrom the solution. When compound ( C ) is treatedwith KCl, orange crystals of compound (D) crystallise out. Identify A to D and also explain the reaction.

When a chromateore (A) is fused with sodium carbonate in free excess o

1.	When a chromateore (A) is fused with sodium carbonate in free excess of air and the product is dissolvedin water, a yellow solution of compound (B)) is obtained. After treatment of this yellow solution with sulphuricacid, compound (C ) can be crystallisedfrom the solution. When compound ( C ) is treatedwith KCl, orange crystals of compound (D) crystallise out. Identify A to D and also explain the reaction.
Answer» Solution :`A= FeCr_(2)O_(4) ,B= Na_(2) CrO_(4) = Na_(2) Cr_(2)O_(7) .2H_(2)O, D=K_(2)Cr_(2)O_(7)` Reactions`: underset((A))(4FeCr_(2)O_(4))+8Na_(2)CO_(3)+ 7O_(2)rarr underset((B))(Na_(2) CrO_(4))+2Fe_(2)O_(3)+8 CO_(2)` `2Na_(2)CrO_(4)+H_(2)SO_(4) rarr underset((C ))(Na_(2)Cr_(2)O_(7)) + Na_(2)SO_(4)+H_(2)O` `underset((C ))(Na_(2)Cr_(2)O_(7)) +2KCL rarr underset((D))(K_(2)Cr_(2)O_(7))+2NaCl`