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MCQ Practice

General Science (Everyday Science) MCQs

Which Earth system reservoir contains the largest fraction of the planet’s freshwater?

  • A. Rivers
  • B. Atmosphere
  • C. Ice sheets and glaciers
  • D. Lakes
Explanation:
Most freshwater is locked in continental ice and glaciers rather than liquid surface waters.

The ozone hole over Antarctica is strongly linked to catalytic destruction by radicals derived from:

  • A. Sulfur dioxide
  • B. Chlorofluorocarbons
  • C. Nitrogen gas
  • D. Carbonate aerosols
Explanation:
Photolysis of CFC-derived halogens generates radicals that destroy stratospheric ozone.

Which statement about radiometric dating is correct?

  • A. It depends on constant atmospheric pressure
  • B. It uses known decay rates of radioactive isotopes
  • C. It works only on sedimentary rocks directly
  • D. It requires fossils in all samples
Explanation:
Isotopic parent-daughter ratios and decay constants allow age estimation.

A confined aquifer differs from an unconfined aquifer because it is:

  • A. Unsaturated
  • B. Bounded above by a low-permeability layer
  • C. Composed only of limestone
  • D. Always shallower
Explanation:
A confining layer restricts flow and can produce artesian pressure.

Which process most directly forms soil horizons over long timescales?

  • A. Instantaneous melting
  • B. Weathering combined with organic accumulation and leaching
  • C. Oceanic spreading
  • D. Lunar tidal forcing
Explanation:
Soil profiles develop from parent material alteration plus biological and hydrologic processes.

El Niño conditions are typically associated with:

  • A. Stronger-than-normal upwelling off western South America
  • B. Weakened trade winds and warmer eastern Pacific surface waters
  • C. Permanent expansion of sea ice
  • D. A stronger Walker circulation
Explanation:
El Niño weakens normal equatorial Pacific circulation and suppresses eastern Pacific upwelling.

The thermocline in the ocean is a zone of rapid change in:

  • A. Salinity only
  • B. Temperature with depth
  • C. pH with latitude
  • D. Nutrients with longitude
Explanation:
The thermocline separates warm surface water from colder deep water by a steep thermal gradient.

Ocean acidification is mainly caused by increased dissolution of atmospheric:

  • A. Nitrogen
  • B. Oxygen
  • C. Carbon dioxide
  • D. Methane only
Explanation:
Dissolved (CO_2) forms carbonic acid, lowering seawater pH.

Which greenhouse gas has the greatest current overall contribution to the natural greenhouse effect?

  • A. Argon
  • B. Water vapor
  • C. Neon
  • D. Helium
Explanation:
Water vapor is the most abundant and influential natural greenhouse gas.

The Hadley cell is primarily driven by:

  • A. Polar cooling only
  • B. Differential solar heating between equator and subtropics
  • C. Tidal friction
  • D. Lunar gravity
Explanation:
Strong equatorial heating drives rising air and tropical atmospheric overturning.