General Science
General Science in PET tests school-level physics, chemistry, biology, and health awareness. Most items ask for a definition, unit, function, or cause-effect link, not calculation-heavy derivation.
Physics basics
- SI unit of force is newton (N); 1 N = 1 kg·m/s².
- Speed is scalar; velocity is vector. Acceleration is change in velocity per unit time.
- Newton’s first law describes inertia; second law gives F = ma; third law states action and reaction are equal and opposite on different bodies.
- Electric current is measured in ampere, potential difference in volt, resistance in ohm.
Chemistry and biology
- pH below 7 is acidic, 7 neutral, above 7 basic. Litmus turns red in acid and blue in base.
- Photosynthesis uses carbon dioxide and water in the presence of chlorophyll and sunlight to make glucose, releasing oxygen.
- Deficiency diseases: vitamin A-night blindness; vitamin C-scurvy; vitamin D-rickets; iron-anaemia; iodine-goitre.
Worked example
A 2 kg object accelerates at 3 m/s². Find the net force. Reasoning: Use Newton’s second law, F = ma. Substitute mass 2 kg and acceleration 3 m/s²: F = 2 × 3 = 6 kg·m/s² = 6 N. The direction of the force is the direction of acceleration. Answer: 6 N.
Traps
Do not confuse mass (kg) with weight (N); weight = mg, so it changes with gravity while mass does not. In pH, a lower number means more acidic, not weaker. In biology, “oxygen released” in photosynthesis comes from water, not carbon dioxide. Check whether the question asks for a unit or a quantity.