This Is a Certified Answer

Certified answers contain reliable, trustworthy information vouched for by a hand-picked team of experts. Brainly has millions of high quality answers, all of them carefully moderated by our most trusted community members, but certified answers are the finest of the finest.
When Hydrogen gas is passed over Copper Oxide, Copper and steam are formed.
                         CuO + H₂ ------------> Cu + H₂O

We take a test tube and keep it in semi-inverted position. Then we pass hydrogen through a small pipe to the copper oxide. The copper being heavier will stay in the test tube and the steam will flow out through the open face of the test tube.
When hydrogen( H₂) gas is passed over copper oxide(CuO ,quick lime) copper(Cu) and steam( H₂O) are formed.The equation is given below.

CuO + H₂ -------->  Cu  +   H₂O

                        (Copper)   (Steam or water)

2 3 2