Atmosphere, Winds & Earth Structure MCQs with Answers
Solved Atmosphere, Winds & Earth Structure MCQs with answers — trades, doldrums, monsoon, layers, crust, mantle & core. Free quiz + PDF for PPSC, FPSC, NTS, CSS & PMS.
Atmosphere, Winds & Earth Structure — Master Reference for Pakistani Competitive Exams
The chapter Atmosphere, Winds & Earth Structure is a high-frequency Everyday Science / Geography topic in Pakistan’s PPSC, FPSC, NTS, CSS, PMS, OTS, CTS, BPSC, KPPSC and SPSC One Paper exams. Almost every Junior Clerk, Tehsildar, Assistant, Sub-Inspector, Lecturer and BPS-14 to BPS-17 paper carries 2–4 MCQs from this chapter — and it is core material for the CSS Screening MPT (General Science & Ability) paper. This page consolidates solved MCQs with answers covering atmosphere composition (78% N₂, 21% O₂, argon), wind systems (trades, doldrums, monsoon, sea breeze, geostrophic, Coriolis force, Buran, Santa Ana, pampero, Beaufort scale), weather instruments (barometer, anemometer, hygrometer), the five atmospheric layers (troposphere, stratosphere, mesosphere, thermosphere/ionosphere, exosphere) and Earth’s internal structure (crust, upper & lower mantle, outer & inner core, lithosphere, asthenosphere, Moho discontinuity). For wider context, see the Wikipedia overview of Earth’s Atmosphere and Structure of the Earth — the most authoritative references for this chapter.
Layers of Earth’s Atmosphere — Quick Reference
| Layer | Height | Boundary | Key Fact |
|---|---|---|---|
| Troposphere | 0–14.5 km | Tropopause | Holds 85–90% of atmospheric mass; jet stream; weather occurs here. |
| Stratosphere | 14.5–50 km | Stratopause | Contains the ozone layer. |
| Mesosphere | 50–85 km | Mesopause | Meteors burn up here; noble gases & iron vapours. |
| Thermosphere | 85–600 km | Thermopause | Also called Ionosphere — hottest layer (up to 4,500°F); reflects radio waves. |
| Exosphere | 600–10,000 km | — | Outermost layer; extremely thin air. |
Earth’s Internal Structure
| Layer | Depth / Thickness | State | Key Fact |
|---|---|---|---|
| Crust | 5–70 km | Solid | Density 2.8 g/cm³; igneous, sedimentary, metamorphic rocks. Boundary = Moho. |
| Upper Mantle | Moho to ~400 km | Solid / plastic | Iron & magnesium silicates. Contains the asthenosphere — zone of weakness. |
| Transition Zone | 400–670 km | Plastic | Minerals undergo a phase transition. |
| Lower Mantle | 670–2900 km | Solid | Magnesium, silicon, iron — denser than upper mantle. |
| Outer Core | 2300 km thick | Liquid | Nickel-iron alloy — controls Earth’s magnetic field. |
| Inner Core | 1200 km thick | Solid | Almost entirely iron; solid despite high temperature due to extreme pressure. |
Key Wind & Weather Facts
- Trades — Wind system in equatorial areas.
- Doldrums — Low-pressure area from 5°N to 5°S of the Equator.
- Monsoon — Has a well-developed cycle in South and Southeast Asia.
- Sea breeze — Wind blowing from sea/ocean inland to coastal land.
- Geostrophic wind — Wind deflected due to Earth’s rotation.
- Coriolis force — Deflects currents to the right in the Northern Hemisphere.
- Buran — A wind of cold air.
- Santa Ana winds — Strong, dry downslope winds of southern California & northern Baja California.
- Pampero — Burst of cold polar air over the pampas (Brazil, Argentina, Uruguay, Paraguay, Bolivia).
- Beaufort scale — Empirical measure relating wind speed to observed conditions.
- Horse latitudes — Subtropical regions known for calm winds and little precipitation.
- Air composition — ~78% nitrogen, ~21% oxygen, plus argon (chemically inactive), CO₂, neon, hydrogen.
- Atmospheric pressure — Caused by Earth’s gravitational pull; measured with a barometer.
- Anemometer — Measures wind speed.
- Hygrometer — Measures humidity.
- Absolute humidity — Actual amount of water vapour present in the atmosphere.
- Advection fog — Forms when warm, moist air passes over a cool surface.
- Smog — Air pollution = smoke + fog.
- Cirrus clouds — Made of ice crystals (also called ice clouds).
- Cumulonimbus — Cumulus clouds associated with thunderstorms and heavy rain.
- Convectional rainfall — Often accompanied by lightning and thunder.
Exam tip: Lock six anchors and you cover ~80% of all MCQs from this chapter — Air = 78% N + 21% O, Argon = chemically inactive gas, 5 atmospheric layers (Tropo → Strato → Meso → Thermo → Exo), Ionosphere = hottest layer + radio waves, Moho = crust/mantle boundary, and Outer core = liquid nickel-iron (magnetic field).
Frequently Asked Questions
Earth’s atmosphere is approximately 78% nitrogen and 21% oxygen, with small amounts of argon, carbon dioxide, neon and hydrogen. Argon is the chemically inactive gas in the atmosphere.
Five layers from bottom to top: Troposphere (0–14.5 km, contains 85–90% of atmospheric mass & the jet stream), Stratosphere (14.5–50 km, ozone layer), Mesosphere (50–85 km, meteors burn here), Thermosphere/Ionosphere (85–600 km, hottest layer), and Exosphere (600–10,000 km, outermost).
Chemically, Earth has four main layers: Crust (5–70 km, alumino-silicates), Mantle (~2900 km deep, ferro-magnesium silicates), Outer Core (2300 km, liquid nickel-iron — controls magnetic field) and Inner Core (1200 km, solid iron).
The Mohorovicic discontinuity (or “Moho”) is the boundary between Earth’s crust and the mantle — a surface at which seismic waves change velocity.
Trades are the wind system in equatorial areas. The Doldrums are a low-pressure area from 5°N to 5°S of the Equator — known for calm, still weather between the trade winds of the two hemispheres.
Yes — essential. Atmosphere, Winds & Earth Structure MCQs are tested in every One Paper, NTS NAT, GAT, OTS, CTS, BPSC, KPPSC, SPSC, PPSC and FPSC exam — and the chapter is core material for the CSS Screening (General Science & Ability) paper. Expect 2–4 MCQs per 100-mark paper.
Yes. Click the Download PDF button to get all Atmosphere, Winds & Earth Structure MCQs with correct answers as a branded QuizWing PDF for offline revision.