The electromagnetic radiation used to kill germs in water purifiers is
Answer & explanation
Correct answer: option 4
The correct answer is Option (4) → Ultraviolet rays
Ultraviolet radiation damages the genetic material of bacteria and viruses, so UV lamps are used in water purifiers to kill germs. UV is easy to produce with lamps and does not make the water radioactive or unsafe.
Option (4) Ultraviolet rays — Correct. UV lamps kill germs in water purifiers.
NCERT (2026-27):
Ultraviolet Rays – “… UV lamps are used to kill germs in water purifiers.”