On passing hydrogen gas over the heated black material coating on the surface of copper sheets- give reason

On passing Hydrogen gas over the heated black material coating on the surface of copper sheets :

It becomes Brown due to copper formation

Explanation:

Copper reacts with atmospheric Oxygen (Moisture) and gets black because of the formation of copper oxide (CuO). This reaction is also called oxidation reaction .

On passing Hydrogen gas over the heated black material coating on the surface of copper sheets this black coating become brown. This is due to formation of Copper again. This is redox- reaction.

Here copper oxide  is reduced  to copper and Hydrogen is oxidised water.

8 m/s because for him to get the same amount of energy as ray is putting out, bobby, who weighs half as much as ray, needs to run twice as fast.