Question

An element is soft and can be cut with a knife. It is very reactive and cannot be kept open in the air. It reacts vigorously with water. The element is most likely to be ______.

पर्याय

• Mg

• S

• P

• Na

Answer 1

An element is soft and can be cut with a knife. It is very reactive and cannot be kept open in the air. It reacts vigorously with water. The element is most likely to be Na.

Explanation:

Sodium (Na) is an alkali metal that is exceptionally soft and can be easily cut with a butter knife. Due to its extreme reactivity with atmospheric oxygen and moisture, it ignites easily in open air and reacts violently with water to form hydrogen gas, so it must be stored in kerosene. Non-metals like sulphur (S) and phosphorus (P) are brittle, while magnesium (Mg) is a harder alkaline earth metal that reacts slowly with water.