Final answer:
Sodium, potassium, and lithium are stored under oil to protect them from reacting with air and moisture. The oil creates a barrier that prevents contact with the reactive metals.
Step-by-step explanation:
Sodium, potassium, and lithium are stored under oil for several reasons. First, these metals are highly reactive and can easily react with air and moisture in the environment. They can even catch fire if exposed to air.
Storing them under oil helps to prevent contact with air and moisture, keeping them safe. Second, these metals are denser than oil, so they sink in oil rather than float on it. This makes it easier to handle and store them, as they are contained within the oil.
For example, in the case of lithium, it floats in paraffin oil because its density is less than the density of the oil. Overall, storing sodium, potassium, and lithium under oil helps to protect them from reacting with air and moisture, ensuring their stability and safety.