Consider that cuo (s) + h2so4 (aq) reacts to give cuso4 (aq) and cuo (s) + k2so4does not give a product.

The given above are to be explained by the series of the reactivity of metals relative to the reactivity of hydrogen. Cu is the symbol for copper and it is less reactive than hydrogen. Thus, hydrogen was able to replace. Also, K is the symbol for potassium which is more reactive than Cu. Hence, the reaction between the given compounds does not give any product.