A brown substance X on heating in air forms a substance Y


#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. Name the substance X and Y.


#2

The substance X is copper. On heating in air, it forms copper oxide Y.

When hydrogen gas is passed over black copper oxide then it turns brown as oxygen is removed by hydrogen.


#3

From which book this question is taken?