Question

A brown substance 'x' on heating in air forms a compound 'y'. When hydrogen gas is passed over 'y', it changes to 'x' again. (a) name substances 'x' and 'y'. (b) name the processes occurring during the two changes.

Answer 1

Copper is the brown substance.

Upon heating copper we get,

2Cu + O2 ⇒ 2CuO

Cuo is black in colour.

On passing hydrogen over CuO we get,

CuO + H2 ⇒ Cu + H2O

Both are redox reactions.