Solution:When you heat a china dish containing 1 gram of copper powder, the black substance formed on the surface of the powder is due to Oxidation.
When copper powder is heated in the presence of air (which contains oxygen), the copper reacts with oxygen to form copper(II) oxide, which is black in color. The chemical reaction is:
+O_2(g)\xrightarrow{heat}2CuO(s))
