Question

Human beings contain oxygen in ______state.

Answer 1

Oxygen occur in a free state-

• It is present in atmospheric air.
• About 21% of air is oxygen.

Oxygen occur in a combined state-

• It is present in water, rocks, minerals and sand.
• It is present in most organic matter.
• It is utilised by plants and animals.

Hence,

Human beings contain oxygen in combined state.