NDA (I) 2021 GAT Q131: Which one of the following is not a form of

Q: What is the answer to NDA (I) 2021 GAT Q131?

D. Correct — D, Sleet. Dew, fog and frost all form when water vapour in the air condenses (or is deposited) directly onto cool surfaces or lingers as suspended droplets — they are forms of condensation. Sleet, however, is a form of precipitation: raindrops that freeze or partly freeze as they fall through a below-freezing layer of air. Because it falls from clouds rather than condensing in place, sleet is the odd one out.

NDA (I) 2021 General Ability Test · Question 131 of 149

Question text verified against the official NDA question paper.

Which one of the following is not a form of condensation?

(a)Dew
(b)Fog
(c)Frost
(d)Sleet

Answer

Why

Correct — D, Sleet. Dew, fog and frost all form when water vapour in the air condenses (or is deposited) directly onto cool surfaces or lingers as suspended droplets — they are forms of condensation. Sleet, however, is a form of precipitation: raindrops that freeze or partly freeze as they fall through a below-freezing layer of air. Because it falls from clouds rather than condensing in place, sleet is the odd one out.

Why the others are wrong

(a)Dew — Dew forms when water vapour condenses on cool surfaces (grass, leaves) once they drop below the dew point at night — a classic form of condensation, so it cannot be the answer.
(b)Fog — Fog is a cloud at ground level: vapour condenses into tiny suspended water droplets when moist air cools near the surface — a form of condensation.
(c)Frost — Frost forms when moisture is deposited as ice crystals on surfaces cooled below freezing point — grouped with the condensation (deposition) processes, not with precipitation.

Concept

Condensation is the change of water vapour into liquid (or, by deposition, into solid) when air is cooled to or below its dew point. Its everyday forms — dew, fog, mist, frost and clouds — occur where the moisture forms in place. Precipitation, such as rain, snow, hail and sleet, is water that falls from clouds to the ground.

Three options (dew, fog, frost) are ground-level condensation phenomena; the fourth, sleet, is precipitation. The discriminator is whether the moisture forms in situ (condensation) or falls from a cloud (precipitation). Sleet falls, so it is not condensation.

Key facts

Condensation forms include dew, fog, mist, frost and clouds.
Dew and frost form on cool surfaces at/below the dew point (frost by deposition into ice).
Fog is suspended water droplets — essentially a cloud at the surface.
Sleet is precipitation: raindrops that freeze or partly freeze while falling.

Forms of condensation vs. forms of precipitation

Dew→Condensation — vapour condenses on cool surfaces

Fog→Condensation — droplets suspended near the ground

Frost→Condensation/deposition — ice deposited on cold surfaces

Sleet→Precipitation — frozen/partly frozen raindrops falling from clouds

Sleet falls as precipitation; it is not a form of condensation — option (d).

Study next

Condensation, dew point and relative humidityForms of precipitation — rain, snow, hail and sleetFormation of clouds, fog and mistAdiabatic cooling and the hydrological cycleDifference between condensation and deposition (frost formation)

Common traps

Treating every kind of atmospheric moisture as 'condensation' — precipitation (sleet, hail, rain) is a separate category.
Confusing frost (a condensation/deposition form) with sleet (a precipitation form).

Asked as 'which is/is not a form of condensation/precipitation', or by classifying dew, fog, frost, sleet and hail.

Related PYQs

UPSC_2002_GS1_Q92002Open & attempt →

Consider the following climatic and geographical phenomena: 1. Condensation 2. High temperature and humidity 3. Orography 4. Vertical wind. Thunder-cloud development is due to which of these phenomena?

(a) 1 and 2
(b) 2, 3 and 4
(c) 1, 3 and 4
(d) 1, 2, 3 and 4

Answer(d) 1, 2, 3 and 4

Same concept — condensation as an atmospheric-moisture process; recognising condensation (vs precipitation) is the reasoning that separates dew/fog/frost from sleet in this question.

NDA_GAT_2025_I_Q922025Open & attempt →

Which of the following statements with reference to Sleet is/are correct? 1. Sleet is frozen raindrops and refrozen melted snow-water. 2. It occurs when a layer of air with the temperature below freezing point overlies a warm layer near the ground surface.

(a) 1 only
(b) 2 only
(c) Both 1 and 2
(d) Neither 1 nor 2

Answer(a) 1 only

Same subject — the nature of sleet as frozen falling raindrops (precipitation), directly reinforcing why sleet is not a form of condensation.

NDA_GAT_2025_I_Q1052025Open & attempt →

Condensation of water vapour into water is influenced by which of the following factor/factors? 1. Volume of air 2. Humidity 3. Temperature Select the answer using the code given below:

(a) 1 only
(b) 1 and 2 only
(c) 2 and 3 only
(d) 1, 2 and 3

Answer(d) 1, 2 and 3

Same concept — the process of condensation itself (what controls when vapour condenses), the definition needed to classify dew, fog and frost as condensation.

Practice

practice — not a real PYQ
Which one of the following is a form of precipitation rather than condensation?
- (a)Dew
- (b)Fog
- (c)Hail
- (d)Frost
Answer(c) Hail — like sleet and rain, it falls from clouds and is precipitation, not condensation.
practice — not a real PYQ
Dew forms when
- (a)raindrops freeze while falling
- (b)water vapour condenses on surfaces cooled to the dew point
- (c)ice pellets fall from clouds
- (d)warm air rises and expands
Answer(b) water vapour condenses on surfaces cooled to the dew point — a form of condensation.