A, B C and D are four metals. Both A and B react with concentrated alkali and also with steam. Reaction of A with steam is rapid in the beginning and becones slow later. Oxide of C on treatment with A liberates huge amount of heat and C produces borwn-coloured flakes on exposure to humid atmosphere. D forms two types of oxides below 1370 K and above 1370 K. Identify A, B, C and D and write all the balanced chemical equations.

A, B C and D are four metals. Both A and B react with concentrated alk

1.	A, B C and D are four metals. Both A and B react with concentrated alkali and also with steam. Reaction of A with steam is rapid in the beginning and becones slow later. Oxide of C on treatment with A liberates huge amount of heat and C produces borwn-coloured flakes on exposure to humid atmosphere. D forms two types of oxides below 1370 K and above 1370 K. Identify A, B, C and D and write all the balanced chemical equations.
Answer» Solution :Since A and B reacts with concentrated alkali, they are Al and Zn. Reaction of A with steam is rapid in the beginning and becomes slow later and hence A is Al. `2H_(2)O+underset((A))2AI+2NaOHtoNaAlO_(2)+2H_(2)uarr` `Zn""underset((B))+NaOHtoNa_(2)ZnO_(2)+H_(2)uarr` `2Al+3H_(2)OtoAl_(2)O_(3)+3H_(2)` `Zn+H_(2)OtoZnO+H_(2)` Since oxide of C produces huge AMOUNT of HEAT with A and FLAKES with humid atmosphere, it is iron. `Fe_(2)O_(3)+2Al""to2Fe+Al_(2)O_(3)+"Heat"` As D forms TWO TYPES of oxides above and below 1370 K, it is Cu. `underset((D))Cu+O_(2)overset(lt1370K)toCu_(2)O` `Cu+O_(2)overset(gt1370K)toCu_(2)O`