Question

An element is soft and can be cut easily with a knife. It is very reactive and cannot be kept open in the air. It reacts vigorously with water. This element is most likely to be: A. magnesium B. potassium C. phosphorous D. aluminium...​

Answer 1

Potassium is soft and cut withan knife easily.

It is highly reactive.

Hence, stored in kerosene

option b is correct

Answer 2

Explanation:

Potassium reacts with water to potassium hydroxide and hydrogen gas. The reaction potassium with water is highly exothermic in nature. It produces a lot of heat energy and this heat energy can cause the hydrogen gas produced during the reaction, to catch ire. In order to keep it safe potassium is stored in kerosene.