What prevents alkaline metals from exploding?

Alkali metals are chemical elements that are highly reactive with oxygen in the air and water. The alkali metals are sodium, potassium, rubidium cesium, and francium. When any of these metals is dropped in water, an explosion takes place with the generation of heat. The alkali metal breaks water into its constituents, hydrogen and hydroxyl ions, and due to the heat, the hydrogen gas catches fire. They react immediately with oxygen in the air to form oxides. Hence pure alkali metals are not found in nature. Due to their highly reactive nature, pure alkali metals are stored in kerosene or mineral oil (paraffin) to prevent an explosion.