Which one among the following metals is not stored under oil?

Correct option is D

The correct answer is (d) Lithium.
Lithium is stored in paraffin wax instead of oil because it's lighter than kerosene and would float to the surface of the kerosene, where it would react with air. While metals like sodium, potassium, and rubidium are highly reactive and stored under oil to prevent them from reacting with moisture and oxygen in the air, lithium does not require storage under oil. Lithium is less reactive compared to these other alkali metals and is often stored in an inert atmosphere or sealed container, but it does not need to be submerged in oil like the others.
Information Booster: ● Sodium, potassium, and rubidium are all alkali metals that react vigorously with water and air, hence stored under oil. ● Lithium, although reactive, reacts slower with moisture and air compared to other alkali metals, so it does not need to be stored under oil. ● The reactivity of alkali metals increases as you go down the group, with rubidium being more reactive than sodium and potassium. ● Storing metals under oil helps to isolate them from air and moisture, preventing dangerous reactions. ● Cesium, another alkali metal not listed here, is also stored under oil due to its high reactivity. ● Lithium is often stored in sealed containers or in an inert atmosphere like argon to prevent oxidation.