A brown substance 'X' on heating in air forms a substance 'Y'. When hydrogen gas is passed over heated 'Y', it again changes back into 'X'. (i) Name the substance 'X' and 'Y'. (ii) Name the type of chemical reactions occuring during both the changes. (iii) Write the chemical equations of the reactions.

A brown substance 'X' on heating in air forms a substance 'Y'. When hy

1.	A brown substance 'X' on heating in air forms a substance 'Y'. When hydrogen gas is passed over heated 'Y', it again changes back into 'X'. (i) Name the substance 'X' and 'Y'. (ii) Name the type of chemical reactions occuring during both the changes. (iii) Write the chemical equations of the reactions.
Answer» Solution :(i) `X-Cu,Y-CuO`. (II) When copper is heated in air, OXIDATION take PLACE. When hydrogen gas is passed over heated copper oxide, reduction takes place. (iii) `2Cu+O_(2)overset(DELTA)rarr2CuO` (Oxidation) `CuO+H_(2)overset(Delta)rarrCu+H_(2)O` (Reduction)