An element A is soft and can be cut with a knife. This is very reactive to air and cannot be kept open in air. It reacts vigorously with water. Identify the element from the following. 

Options

A. Mg
B. Na
C. P
D. Ca

Answer

B

Explanation

Sodium is so soft that can be cut using a knife. It reacts with oxygen or moisture present in air readily and reacts with water: Vigorously. Because of this sodium is stored in kerosene oil to prevent any reaction or accidents