The reactivity of metals is determined by their position in the reactivity series. Iron is a more reactive metal than zinc or copper, which means it is more likely to undergo chemical reactions, including the reaction with sulfuric acid. As a result, the reaction between iron and sulfuric acid releases more heat energy, leading to a higher rise in temperature.
In summary, the lower reactivity of zinc and copper compared to iron results in a smaller amount of heat energy released during their reactions with sulfuric acid. This explains why the rise in temperature obtained with zinc and copper sulfate is not significantly higher than iron sulfate.
