All Free Everyday Science MCQs with Answers

831. The yellow colour in photochemical smog is due to the presence of____________?

• A. Sulphur dioxide
• B. Carbon dioxide
• C. Nitrogen dioxide
• D. CFC's

Explanation: Nitrogen dioxide gives photochemical smog its characteristic yellow-brown colour and is produced largely by vehicle combustion. Sulphur dioxide is associated more with industrial pollution and acid rain.

832. "Ornithology" is the study of_____________?

• A. Birds
• B. Insects
• C. Sea Plants
• D. Sea Animals

Explanation: Ornithology is the branch of zoology concerned with birds, including their classification, behaviour and distribution. The study of insects is entomology.

833. Wind always blows from area of ________?

• A. Low pressure to high pressure
• B. High pressure to low pressure
• C. Only low pressure
• D. Only high pressure

Explanation: Air moves because of pressure differences, generally flowing from regions of high pressure toward regions of low pressure. Unequal heating of Earth's surface creates many of these differences.

834. The density of Air is_____________?

• A. 0.225 kg/m3
• B. 1.025 kg/m3
• C. 1.225 kg/m3
• D. 1.425 kg/m3

Explanation: At about sea level and room temperature, dry air has a density near 1.225 kg/m³. Its density changes with temperature, pressure and humidity.

835. The hard, solid rocks, whose composition or texture has been changed by heat or pressure in the Earth are called____________?

• A. Sedimentary rocks
• B. Metamorphic rocks
• C. Igneous rocks
• D. All of the above

Explanation: Metamorphic rocks form when existing rocks are altered by heat, pressure or chemically active fluids without completely melting. Sedimentary rocks form from deposited material, while igneous rocks solidify from molten rock.

836. In which layer of atmosphere does commercial aircrafts usually fly?

• A. Stratosphere
• B. Troposphere
• C. Mesosphere
• D. Thermosphere

Explanation: Long-distance commercial aircraft commonly cruise in the lower stratosphere, above much of the weather and turbulence of the troposphere. The exact altitude varies with aircraft, route and conditions.

837. Water vapour beyond the dew point result in_________?

• A. Precipitation
• B. Hailstorm
• C. Condensation
• D. Formation of ice

Explanation: At the dew point, air is saturated with water vapour, so additional cooling or vapour causes condensation into liquid droplets. Clouds, fog and dew are common results of this process, while precipitation requires droplets or ice particles to grow and fall.

838. What is the effect of height increase over temperature?

• A. Temperature increase
• B. Temperature decrease
• C. Remains constant
• D. None

Explanation: In the lower atmosphere, temperature generally decreases as altitude increases because air pressure falls and rising air expands and cools. This is why high mountain regions are colder than nearby lowlands.

839. International date line passes through which strait?

• A. Malacca Strait
• B. Adam Strait
• C. Bering Strait
• D. Java Strait

Explanation: The International Date Line broadly follows the 180° meridian and passes through the Bering Strait. It bends around islands and countries to avoid dividing populated areas.

840. Bamboo is a__________?

• A. Herb
• B. Grass
• C. Shurb
• D. Tree

Explanation: Bamboo is a type of grass in the family Poaceae, despite its tall, woody, tree-like appearance. Its hollow stems and rapid growth help distinguish it from true trees.