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CBSE · Class 11 · Social Science

Water in the Atmosphere

Standard difficulty · 20 questions · 40 marks · Time: 37 minutes

Name: Date: Score: ____ / 40

Write full answers in Sections B and C. Answers are on the last page — try every question first!

Section A — Choose the correct answer8 × 1 = 8 marks
1.
Water vapour in the air varies from zero to about:
  1. 0.04 per cent by volume
  2. 78 per cent by volume
  3. 40 per cent by volume
  4. 4 per cent by volume
2.
Which describes frost?
  1. fog mixed with smoke
  2. more moist than fog, visibility 1–2 km
  3. ice crystals on cold surfaces, with the dew point at or below freezing
  4. a cloud at the ground, visibility under 1 km
3.
Which describes cirrus clouds?
  1. layered clouds covering large parts of the sky
  2. cotton-wool clouds with flat bases at 4,000–7,000 m
  3. thin, feathery white clouds at 8,000–12,000 m
  4. ice crystals lying on the ground
4.
What causes cyclonic rain?
  1. air rises along fronts in cyclones
  2. moist air is forced up a mountain
  3. the sun heats the sea at night
  4. heated air rises in convection currents
5.
At its temperature, air could hold 50 g of water vapour per cubic metre, but holds 48 g. What is its relative humidity?
  1. 106 %
  2. 4 %
  3. 48 %
  4. 96 %
6.
A room is 4 m × 7 m × 4 m, and the air in it has an absolute humidity of 19 g per cubic metre. How many grams of water vapour are in the room?
  1. 2,128 g
  2. 532 g
  3. 285 g
  4. 112 g
7.
Condensed moisture near the ground limits visibility to 100 m. What is it?
  1. fog
  2. frost
  3. mist
  4. clear air (visibility over 2 km)
8.
A region receives 438 cm of precipitation a year. In which rainfall regime does it fall?
  1. under 50 cm (low)
  2. 50–100 cm
  3. 100–200 cm (moderate)
  4. over 200 cm (heavy)
Section B — Short answer8 × 2 = 16 marks
9.
Distinguish between absolute and relative humidity.
10.
Describe each form of condensation: (a) mist (b) fog
11.
Is each cloud high, middle, low or of vertical development? (a) cumulonimbus (b) altocumulus
12.
Describe each form of precipitation: (a) hail (b) sleet
13.
Find the relative humidity: (a) capacity 10 g/m3, holding 4 g/m3 (b) capacity 20 g/m3, holding 2 g/m3. Which air is closer to saturation?
14.
A hall holds 250 m3 of air that could hold 18 g of vapour per m3 but holds 16 g per m3. How many more grams of vapour would saturate it?
15.
On a calm, clear night, will moisture be deposited as dew or as frost if the dew point is (a) 7 °C (b) 2 °C?
16.
Describe each type of cloud: (a) nimbus (b) cirrus
Section C — Longer answers4 × 4 = 16 marks
17.
Describe the forms of condensation.
18.
Match each with its description: (a) nimbus (b) cirrus (c) stratus. Choose from: dark, dense, shapeless rain clouds near the surface; thin, feathery white clouds at 8,000–12,000 m; layered clouds covering large parts of the sky.
19.
A room is 12 m × 7 m × 5 m. Its air could hold 25 g of vapour per m3 and holds 13 g per m3. (a) What is the relative humidity? (b) How many grams of vapour are in the room? (c) What happens if the room cools below its dew point?
20.
A station on the windward slope of a mountain range gets 340 cm of rain a year; one on the leeward side gets 89 cm. (a) How many cm more does the windward station get? (b) About how many times as much, to one decimal place? (c) Explain why the leeward side is dry.
AmbifulWorksheets
Practice that never repeats
CBSE · Class 11 · Social Science

Answer key

Water in the Atmosphere · AW-11SS-GWA-2026-V1 · For parents — fold back or tear off before handing the sheet to your child.

QAnswerWorking
1(d) 4 per cent by volume—
2(c) ice crystals on cold surfaces, with the dew point at or below freezing—
3(c) thin, feathery white clouds at 8,000–12,000 m—
4(a) air rises along fronts in cyclones—
5(d) 96 %48 ÷ 50 × 100
6(a) 2,128 g4 × 7 × 4 × 19
7(a) fogfog: under 1 km; mist: 1–2 km
8(d) over 200 cm (heavy)—
9Absolute humidity is the weight of water vapour per unit volume of air; relative humidity is the percentage of moisture present compared with the air’s full capacity at that temperature.—
10(a) more moist than fog, visibility 1–2 km (b) a cloud at the ground, visibility under 1 km—
11(a) vertical (b) middle—
12(a) rounded ice with concentric layers (b) frozen raindrops or refrozen melted snow—
13(a) 40% (b) 10%; air (a)4 ÷ 10 × 100; 2 ÷ 20 × 100
14500 g(18 − 16) × 250
15(a) dew (b) dewdew point above freezing: dew; at or below: frost
16(a) dark, dense, shapeless rain clouds near the surface (b) thin, feathery white clouds at 8,000–12,000 m—
17Dew on cool surfaces above freezing; frost as ice crystals below freezing; fog and mist as cloud near the ground; and clouds in the free air.—
18(a) dark, dense, shapeless rain clouds near the surface (b) thin, feathery white clouds at 8,000–12,000 m (c) layered clouds covering large parts of the sky—
19(a) 52% (b) 5,460 g (c) The excess vapour condenses into droplets (dew or mist).13 ÷ 25 × 100; 420 × 13
20(a) 251 cm (b) about 3.8 times (c) Descending air warms, so its capacity to hold moisture rises and it gives little rain: a rain-shadow area.340 − 89; 340 ÷ 89