SSC CGL 2025 Tier-I · 19 September 2025, Shift 1 · General Awareness · Question 25 of 100

We transcribed this text from the pictures on a candidate's response sheet for this shift; the answer is the key SSC colour-marked on that sheet. Solution last reviewed 11 September 2026.

Where this paper and its answers come from

SSC does not publish CGL question papers or a public answer key. From 2025 the candidate response sheet prints every question and option as a picture, so the text here is transcribed from those pictures for this shift and checked against them independently; where the layout carries meaning, the picture is shown as well. Each answer is the key SSC colour-marked on that sheet. SSC released a tentative key for challenge and later its final one, both only to candidates behind a login, and the sheet does not say which of the two it carries. The solutions are written by UnlockIAS.

Which matched pair is incorrect?

(a)Mesosphere - meteors burn
(b)Stratosphere - ozone layer
(c)Exosphere - tropospheric clouds
(d)Thermosphere - ISS orbit

Answer

Why

Correct — C. Test each pair against its layer.

(a) Mesosphere: most meteors burn up here. Correct pair.
(b) Stratosphere: holds the ozone layer. Correct pair.
(c) Exosphere: the thin outermost layer. Clouds form in the troposphere. Incorrect pair.
(d) Thermosphere: the ISS orbits within it. Correct pair.

The incorrect pair is Exosphere - tropospheric clouds → option (c).

Why the others are wrong

(a)
Mesosphere - meteors burn — This pair is correct. Most meteors vaporise in the mesosphere, which NCERT places above the stratosphere up to about 80 km, where the air is thick enough to slow and burn them.
(b)
Stratosphere - ozone layer — This pair is correct. The ozone layer sits in the stratosphere, which extends up to about 50 km. It absorbs ultraviolet radiation and shields life on Earth.
(d)
Thermosphere - ISS orbit — This pair is correct. The International Space Station orbits at about 400 km, inside the thermosphere, which extends from about 90 km to between 500 and 1,000 km.

Concept

NCERT divides the atmosphere into five layers by temperature: troposphere, stratosphere, mesosphere, thermosphere and exosphere.

The troposphere averages 13 km in height, about 8 km at the poles and 18 km at the equator. It holds the dust and water vapour, so weather happens here.

The stratosphere reaches about 50 km and the mesosphere about 80 km. The ionosphere, from 80 to 400 km, lies within the thermosphere. The exosphere is the highest, most rarefied layer.

Clouds are not confined to the troposphere: noctilucent clouds, also called polar mesospheric clouds, sometimes form in the mesosphere near the poles. But the pair says tropospheric clouds, which by name belong to the lowest layer, and the exosphere is far too thin for clouds.

Key facts

Troposphere: about 8 km high at the poles and 18 km at the equator, and all weather happens in it.
Stratosphere: up to about 50 km, containing the ozone layer that absorbs ultraviolet radiation.
Mesosphere: up to about 80 km, where most meteors burn up and temperature falls to about −100°C.
Thermosphere: the International Space Station orbits within it.

Study next

How temperature changes with height in each layerThe ionosphere and the reflection of radio wavesWhy the troposphere is thickest at the equator

Common traps

Placing the ISS in the exosphere because it is in space: at about 400 km it orbits within the thermosphere.
Putting meteors in the thermosphere: most burn up lower, in the mesosphere.

The thermosphere is also tested at 15 Sep 2025, 12:30, GA Q.25, on heating during solar storms, keyed UV and X-ray absorption. The ozone layer appears at 11 Sep 2024, 09:00, GA Q.20, keyed ultraviolet radiation.

Related PYQs

No directly related past PYQ was found.

Topic: Geography — all 135 SSC CGL questions on it, every solved shift.