SSC CGL 2025 Tier-I · 15 September 2025, Shift 2 · 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.

What is the most likely reason for temperature increase in the thermosphere during solar storms?

(a)Molecular friction
(b)UV and X-ray absorption
(c)Convection currents
(d)Cloud condensation

Answer

Why

Correct — B. The thermosphere is heated from above. UCAR's atmosphere guide notes that much of the Sun's X-ray and UV radiation is absorbed there.

When the Sun is very active, as in solar storms, it emits more of that high-energy radiation. The thermosphere absorbs more, gets hotter and expands, or puffs up → option (b).

Why the others are wrong

(a)
Molecular friction — Friction is not the heat source UCAR gives for this layer. Its account puts the heating on absorbed X-ray and UV radiation, which rises when the Sun is active.
(c)
Convection currents — Convection moves heat; it does not create it. NCERT ties strong convection currents to the troposphere, while in the thermosphere temperature rises with height, heated from above.
(d)
Cloud condensation — Clouds need water vapour, which NCERT places in the troposphere, where weather happens. The thermosphere begins about 90 km up, far above any weather.

Concept

Temperature changes direction layer by layer. It falls with height in the troposphere, rises in the stratosphere as the ozone layer absorbs UV, falls in the mesosphere to about −100 °C at 80 km, then rises again in the thermosphere.

UCAR puts the thermosphere from about 90 km to between 500 and 1,000 km up. The air there is so thin that most of the layer is what we normally think of as outer space.

Solar storms matter in practice. As the heated thermosphere expands, the thin air at orbital heights drags on satellites.

Key facts

Much of the Sun's X-ray and UV radiation is absorbed in the thermosphere.
The thermosphere is roughly 500 °C hotter when the Sun is very active than at other times, per UCAR.
The International Space Station orbits within the thermosphere.
The aurora occurs mainly in the thermosphere.

Study next

The ionosphere and the reflection of radio wavesSpace weather: solar flares, CMEs and their effects on satellites and power gridsThe temperature profile of the five atmospheric layers

Common traps

Carrying troposphere processes upward: convection and cloud condensation belong to the weather layer, not the thermosphere.
Reading a high temperature as air that would feel hot, when the thermosphere is so thin it is mostly what we think of as outer space.

Space weather's effects are asked at 17 Sep 2025, 16:00, GA Q.25, where altering ocean currents is keyed as not a consequence. Layer facts are matched at 19 Sep 2025, 09:00, GA Q.25, including thermosphere with the ISS orbit.

Related PYQs

No directly related past PYQ was found.

Topic: Scientific Research — all 178 SSC CGL questions on it, every solved shift.