An element A is soft and can be cut with a knife

• GC Metals Non-Metals

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 

1. Mg
2. Na
3. P
4. Ca

Answer

Sodium is a soft, reactive alkali metal.

The correct option is B.