The ozone layer in the earth’s atmosphere is crucial for human survival because it
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → absorbs most of the ultraviolet radiation from the sun
Option (1) has ions — Incorrect. Ozone \( (\mathrm{O_3}) \) is made of neutral molecules. Ions would not protect living beings in any way.
Option (2) reflects radio signals — Incorrect. Radio signals do no harm to living beings. So reflecting them would play no part in our survival.
Option (3) absorbs most of the ultraviolet radiation from the sun — Correct. The sun is an important source of ultraviolet (UV) radiation, which in large quantities has harmful effects on humans. Most of it is absorbed in the ozone layer, so only a small part reaches the ground.
Option (4) reflects infrared rays — Incorrect. Infrared from the sun reaches the earth’s surface and keeps it warm. The ozone layer does not reflect it. Its protective role is with ultraviolet light.
NCERT (2026-27):
Ultraviolet Rays – “… The sun is an important source of ultraviolet light. But fortunately, most of it is absorbed in the ozone layer in the atmosphere at an altitude of about 40 – 50 km. UV light in large quantities has harmful effects on humans.”