General Science MCQ Practice

• Correct answer: A — The acceleration due to gravity at the equator is less than at the poles.
• Reason: The Earth’s rotation creates a centrifugal acceleration that reduces effective gravity at the equator.
• Key concept: Effective gravity g_eff = g − ω^2R, where ω is angular speed and R is radius.
• Note: Equator has larger radius, so centrifugal term ω^2R is bigger there.
• Exam tip: Remember g_eff < g at equator (due to rotation).
• Why others incorrect: B would ignore rotation; C ignores centrifugal effect; D incorrect because centripetal (rotation) changes g_eff.

• Key concept: U-235 is a fissile isotope that undergoes fission with slow (thermal) neutrons, releasing energy and neutrons to sustain a chain reaction.
• Why others are incorrect: U-238 is mostly fertile (becomes Pu-239); U-234 and U-236 are not practical fissile fuels for reactors.
• Formula/logic (brief): E = energy from fission; one fission event releases ~200 MeV and about 2–3 neutrons.

• The Curie point is the temperature at which a ferromagnetic material loses its permanent magnetic properties and becomes paramagnetic.
• Key concept: magnetic ordering disappears above Curie temperature.
• Formula/idea: below Curie, spontaneous magnetization exists; above it, thermal agitation randomizes spins.
• Correct answer: B
• Why others are incorrect: A – radioactivity is not related; C – conductivity may change but not at Curie; D – transmutation is nuclear, not magnetic.

• Correct answer: D TEL is an antiknock compound, added to gasoline to prevent engine knocking by stabilizing the flame front and reducing premature detonation.
• Key concept: It boosts the octane rating of fuel, improving smooth combustion. Mechanism involves lead compounds scavenging free radicals during combustion.
• Why the others are wrong: A) Not a catalyst; fuels burn without it acting as a catalyst. B) Not an antioxidant in this context. C) Not a reductant.
• Exam tip: Remember “antiknock” = reduces knocking; TEL was used in leaded gasoline, now phased out in many regions.

• Key concept: Cartography is the science and art of making maps, combining geography, design, and measurement.
• Why correct: It specifically refers to map creation, while other terms refer to related activities: remote sensing (data from sensors), photogrammetry (measuring from photos), and mapping is a general term for creating maps.
• Tip: Remember “carto” = map, “graphy” = writing/drawing.
• Incorrect options: A) remote sensing uses satellites; C) photogrammetry measures from photos; D) mapping is broader, not the precise discipline.

• Key concept: at the fusion point (0°C for water), solid and liquid water are in phase equilibrium. Temperature stays constant while both phases coexist.
• Correct answer: C. No net change occurs because melting and freezing happen at the same rate when the temperature is exactly 0°C and pressure ~1 atm.
• Why others are wrong: A would require heat input to melt all ice; B would require heat removal to freeze all water; D implies unequal rates, which isn’t the case at equilibrium.
• Exam tip: remember phase-change points show coexistence with no overall change in amount between phases.

• Correct answer: D they generate ultrasonic sound waves

Key concept: Echolocation. Bats emit high-frequency (ultrasonic) sounds and listen to echoes to map surroundings and detect prey in darkness.

• Distance to an object ≈ (speed of sound × round-trip time) / 2

Exam tip: Distinguish echolocation (sound-based navigation) from vision or light-based cues.

• Why others are incorrect: A is inaccurate—bats largely rely on sound, not vision in the dark. B and C are irrelevant to navigation in darkness.

• Concept: Advection is horizontal transport of heat by the bulk motion of air. It moves energy from one place to another without changing the air’s temperature via mixing, unlike vertical processes.
• Why others are incorrect:
  • Conduction: heat transfer through contact, typically vertical in the atmosphere, not bulk horizontal transport.
  • Convection: vertical movement due to buoyancy, not horizontal advection.
  • Absorption: energy uptake by atmospheric components, not transfer by motion.

Exam tip: Recall advection = transport by wind; convection = upward/downward movement.

• Correct answer: A. arboreal
• Explanation: "Arboreal" means living in trees. Animals that inhabit tree trunks and branches are adapted to tree-dwelling habitats.
• Key concept: Habitat terminology; arboreal refers to trees, volant to flying, amphibious to water/land, aquatic to water.
• Exam tip: Remember root word "arb-" relates to trees (arbor).
• Why others are incorrect: Volant = flying; Amphibious = both land and water; Aquatic = aquatic environments, not specifically trees.

• Why: Cellular respiration releases energy by breaking down glucose in the presence of oxygen, producing ATP. It is an exothermic process.
• Key concept: Energy release occurs as chemical bonds are broken and new bonds form in CO2 and H2O, yielding ATP (energy currency).