Non-stoichiometric cuprous oxide, `Cu_2O` can be prepared in laboratory. In this oxide, copper to oxygen ratio is slightly less than `2:1`. Can you account for the fact that this substance is a p-type semiconductor?.

A student performed following two activities in school laboratory: Activity 1: Addition of zinc dust into copper sulphate solution taken in a test tube. Activity 2: Addition of an iron nail into copper sulphate solution taken in a test tube. He noted down his observations and concluded that chemical reaction occurs in both the cases based on the observed colour change of the resulting solution. Based on these activities, what can you conclude about the reactivity of elements zinc and iron as compared to that of copper?