PPSC Past Papers & Solved MCQs

The correct answer is To use it as an alternative source of energy because nuclear power is harnessed globally to produce clean, massive amounts of base-load electricity without burning fossil fuels.

• Step 1 (Power Generation): Commercial nuclear power plants utilize controlled nuclear fission reactions—typically involving uranium atoms—to boil water into high-pressure steam, which spins large turbines to generate electricity as a stable alternative to coal, oil, and gas.
• Incorrect Options:
  • To kill the enemy nation is incorrect because nuclear weapons represent a destructive military application, which is entirely distinct from the peaceful, civil purpose of energy generation.
  • To waste the excessive energy is incorrect because nuclear technology is designed to produce and conserve power efficiently, not to intentionally dump or waste resources.
  • To cause mutation for people who are working is incorrect because strict industrial safety regulations, heavy shielding, and containment systems are explicitly designed to protect workers from radiation exposure.

The correct answer is Rabies because hydrophobia, which literally translates to the fear of water, is a hallmark clinical sign that develops during the advanced stages of a furious rabies infection.

• Step 1 (Pathology of Hydrophobia): The rabies virus is a neurotropic pathogen that targets the host's central nervous system . As the infection progresses to the brainstem, it severely affects the cranial nerves responsible for controlling the synchronization of respiration and swallowing .
• Step 2 (The Hydrophobic Spasm): When an infected person attempts to drink or even hears liquids, it triggers violent, excruciatingly painful involuntary spasms of the diaphragm and laryngeal throat muscles . This severe physical distress creates a profound psychological dread and systematic avoidance of water .
• Incorrect Options:
  • Malaria is incorrect because it is a mosquito-borne parasitic disease characterized by cyclic high fevers, chills, shaking, and anemia rather than neuromuscular swallowing failures.
  • Cholera is incorrect because it is an acute bacterial intestinal infection caused by consuming contaminated food or water, resulting in severe watery diarrhea and rapid dehydration.
  • AIDS is incorrect because Acquired Immunodeficiency Syndrome is a chronic, life-threatening condition caused by HIV that breaks down the immune system, opening the body to opportunistic infections.

The correct answer is Salt because sodium chloride (NaCl) is the precise chemical name for common table salt used daily in cooking and food preservation.

• Step 1 (Chemical Composition): Sodium chloride is an ionic compound made up of equal parts of the elements sodium (Na) and chlorine (Cl). It crystallizes into cubic structures and is essential for biological life, regulating fluid balances and nerve impulses.
• Incorrect Options:
  • Baking soda is incorrect because baking soda is the common name for an entirely different chemical compound, sodium bicarbonate (NaHCO3).
  • Sugar is incorrect because sugar is a carbohydrate organic compound, typically sucrose (C12H22O11), derived from plant sources.
  • None of these is incorrect because salt is the exact household name for this mineral.

The correct answer is Vitamin D because human skin naturally synthesizes this crucial nutrient when exposed to ultraviolet B (UVB) radiation from the sun.

• Step 1 (Biological Synthesis): When solar UVB rays strike the skin, they interact with a pre-existing compound called 7-dehydrocholesterol. This interaction triggers a chemical conversion that turns the compound into Vitamin D3 (cholecalciferol), which the liver and kidneys later activate.
• Incorrect Options:
  • Vitamin A is incorrect because it is a fat-soluble vitamin obtained directly through dietary sources like animal liver or plant-based carotenoids, not through solar radiation.
  • Vitamin C is incorrect because it is a water-soluble antioxidant that humans must ingest through foods like citrus fruits, as our bodies cannot synthesize it.
  • Vitamin E is incorrect because it represents a group of fat-soluble compounds found in nuts, seeds, and vegetable oils that function as cellular antioxidants.

The correct answer is Newton because Sir Isaac Newton formally published the mathematical laws governing gravity in his groundbreaking 1687 work, Philosophiae Naturalis Principia Mathematica.

• Step 1 (The Scientific Principle): Newton's Law of Universal Gravitation states that every particle of matter in the universe attracts every other particle with a force that is directly proportional to the product of their masses and inversely proportional to the square of the distance between their centers.
• Incorrect Options:
  • Dalton is incorrect because John Dalton is famous for pioneering modern atomic theory and researching color blindness, not gravitation.
  • Einstein is incorrect because Albert Einstein developed the Theory of General Relativity, which describes gravity as the curvature of spacetime rather than postulating the initial universal law.
  • None of these is incorrect because Newton is the exact historical scientist responsible for this law.

The correct answer is Altering human beings by changing their genetic components because eugenics is historically defined as a movement and study aimed at modifying the genetic composition of human populations.

• Step 1 (Etymology and Concept): Coined in the 19th century, the term eugenics stems from Greek roots meaning 'good creation' or 'well-born'. It represents theories and practices that attempted to influence human hereditary traits by selectively encouraging or discouraging specific reproductive outcomes.
• Incorrect Options:
  • Water diseases is incorrect because the study of waterborne pathogens and related public health infections falls under epidemiology and microbiology.
  • Study of flowers is incorrect because the scientific study of plants, including flowers, is called botany or floriculture.
  • Water sports is incorrect because water sports represent recreational or competitive physical activities performed in or on water, completely unrelated to genetic sciences.