Which of the following metals reacts vigorously with cold water?

Potassium is a highly reactive alkali metal. When it comes in contact with cold water, it reacts violently, releasing hydrogen gas (H2) and forming potassium hydroxide (KOH). This reaction is often accompanied by a flame due to the ignition of the hydrogen gas. Aluminium, zinc, and iron are less reactive metals. They may react with steam or very hot water, but their reaction with cold water is not vigorous. Aluminium forms a thin oxide layer that passivates the surface, hindering further reaction with cold water. Zinc and iron react slowly with cold water, producing hydrogen gas at a much slower rate.