General Science MCQ Practice

• Why: Adolf Gaston Eugen Fick invented the first eyeglass-like contact lens to be worn on the eye in 1888. The key concept is creating a curved, close-fitting optical surface that rests on the eye without surgery.
• Other options:
  • A. Enrico Fermi – physicist, not eye lenses.
  • C. Sandford Fleming – time zones, not lenses.
  • D. Benoit Fourneyron – hydraulic machinery, not lenses.

Exam tip: Remember Fick as the pioneer of the first wearable contact lens.

• Correct reasoning: Metrology is the science of measurement and measurement systems—defining units, accuracy, precision, and standards.
• Key concept: It deals with how we quantify physical quantities and ensure comparability across times and places.
• Why others are incorrect:
  • A (Weather) relates to atmospheric conditions, not metrology.
  • C (Distance) is a quantity; metrology covers measuring all quantities, not just distance.
  • D (None) is false since metrology specifically means measurement science.
• Exam tip: Remember metrology = measurement science; relate to standard units (SI) and calibration.

• Answer: B. Lactometer

The lactometer measures the density (specific gravity) of milk. Since pure milk has a higher density than adulterated milk, the lactometer reading differs from standard values.

• Key concept: Specific gravity (SG) = density of milk / density of water. Higher SG indicates higher quality/purity within limits.
• Why others are incorrect: Electrometer checks electrical properties; radiometer uses radiation; refractometer measures refractive index (sugar/fat content, not purity by adulteration).

Exam tip: Compare lactometer reading to standard purity table; small deviations indicate adulteration.

• Correct answer: C
• Explanation: J. J. Thomson discovered the electron in 1897 using a cathode-ray tube, showing particles with negative charge and determining the charge-to-mass ratio e/m by deflecting rays with electric and magnetic fields.
• Key concept: Subatomic particles with charge; measurement of e/m helped identify electrons.
• Tip: Remember the plum pudding model association with Thomson’s discovery.
• Why others are incorrect: Fermi, Noyce, and Dyson are not credited with discovering the electron (Fermi: nuclear/particle theory; Noyce: integrated circuits; Dyson: vacuum cleaner inventor).

• Explanation: Alfred Nobel invented Dynamite by stabilizing nitroglycerin with an absorbent material (diatomaceous earth called kieselguhr). This transformed a highly unstable explosive into a safe, practical one.
• Key concept: chemical stabilization and controlled explosive handling.
• Why others are incorrect: Dunlop, Simons, and Hargreaves are not associated with the invention of dynamite.
• Exam tip: Remember Nobel’s major invention was Nobel Prize founder as well as dynamite inventor.

• Concept: Deciduous trees shed their all leaves once a year, typically in autumn/winter.
• Why not others? Coniferous and evergreen trees keep most or all needles leaves year-round; they do not shed completely once yearly.
• Key point: “Shed leaves once a year” is the defining trait of deciduous trees.
• Tip: If the question emphasizes annual leaf loss, choose deciduous.

• Key concept: Gravity varies with latitude because Earth is an oblate spheroid and rotation adds centrifugal force that reduces effective gravity more at the equator.
• Reason: At the poles, centrifugal force is minimal and radius is smallest, so the gravitational acceleration (g) is strongest.
• Formula note (conceptual): Effective gravity g_eff ≈ g − ω^2R cos^2(latitude); maximum where the centrifugal term is smallest (poles).
• Exam tip: Remember g is largest where rotation has least effect; smallest at equator.
• Why others are incorrect: Equator and tropics have greater centrifugal reduction; poles do not.

• Why correct: The Red Data Book compiles data on endangered (threatened) species to monitor their conservation status.
• Key concept: Conservation biology and IUCN threat categories (e.g., endangered, vulnerable, extinct in the wild).
• Note on options: It is not a list of all plant or all animal species, nor only extinct species.
• Exam tip: Remember “Red Data Book = endangered species” for quick recall.

• Argon is an inert gas, belonging to the noble gases group with a complete outer electron shell, making it chemically very unreactive under normal conditions.
• Key concept: inert gases have stable electron configurations (noble gas configuration) and form few or no compounds.
• Why others are not inert:
  • Hydrogen can react to form many compounds (H2, acids, hydrocarbons).
  • Nitrogen, though relatively unreactive, forms N2 and can react under certain conditions (fertilizers, explosives).
  • Oxygen is highly reactive and supports combustion.
• Exam tip: recall “noble gases” (He, Ne, Ar, Kr, Xe, Rn) as the truly inert ones.