A layer in the Earth's atmosphere called Ionosphere facilitates radio communication. Why? Which of the statements given above is/ are correct?

Answer: (b) 2 only

Long-wavelength radio waves are reflected by the ionised layer.

Statement by statement

1. ✗ WRONG Radio waves bounce off the ionosphere’s charged particles (ions), not ozone.

2. ✓ CORRECT Radio waves have long wavelengths, which the ionosphere reflects back.

The idea

Solar radiation removes electrons from some atmospheric particles, producing an ionised region. Its free electrons can bend suitable radio waves back towards Earth. The effect depends on frequency and the state of the layer. A radio wave’s long wavelength by itself does not guarantee that every band is returned.

Solar energy ionises upper air → Free electrons affect a radio wave → Suitable frequencies bend progressively → The wave returns towards Earth → Communication extends beyond the horizon

Why the others are wrong

(a) Credits ozone.

(c) Credits ozone.

(d) Rejects the wavelength point.

The trap

Ozone is the famous atmospheric layer — but it absorbs UV, it doesn’t reflect radio.

Elimination technique

Match each layer to its function: ozone absorbs ultraviolet, while ionised particles affect radio propagation. Statement 1 assigns the wrong mechanism, so remove (a) and (c); the wavelength statement then needs the question’s radio-communication context.

Also know

The ionosphere overlaps parts of the mesosphere and thermosphere rather than forming a separate temperature-defined layer. Its D, E and F regions change between day and night. Shortwave radio can use this skywave path; many higher-frequency signals pass through to satellites. Ozone is mainly a stratospheric ultraviolet absorber, not the radio-return mechanism.