A student investigates the reactivity of four metals: aluminium, iron, platinum, and potassium. Using knowledge of the reactivity series, describe what would be observed when each metal is separately placed in dilute sulfuric acid, and explain the pattern in terms of reactivity.

Potassium reacts very vigorously, even explosively, with dilute sulphuric acid – the reaction is too dangerous to test safely.
Aluminium reacts with dilute sulphuric acid, producing bubbles of hydrogen and fizzing; the reaction is vigorous.
Iron also reacts with dilute sulphuric acid, giving hydrogen bubbles, but the reaction is less vigorous than that of aluminium.
Platinum shows no reaction with dilute sulphuric acid – there is no change.

The pattern follows the reactivity series: metals higher in the series (potassium, aluminium, iron) displace hydrogen from the acid more readily because they lose electrons more easily and are stronger reducing agents, whereas platinum, below hydrogen in the series, does not displace hydrogen and remains unreactive.