General Science
The General Science domain checks class 8–10 physics, chemistry and biology, mostly as one-line factual questions, though simple speed, work and electricity calculations do appear.
Physics
- SI units: force in newton, work and energy in joule, power in watt, pressure in pascal.
- Speed is scalar, velocity is vector; the slope of a distance–time graph gives speed.
- Light: a plane mirror forms a virtual, laterally inverted image of the same size; a convex lens converges, a concave lens diverges.
- Ohm's law V = IR; household appliances are wired in parallel so each receives full supply voltage.
Chemistry
- Common salt NaCl, baking soda NaHCO₃, washing soda Na₂CO₃·10H₂O, quicklime CaO, plaster of Paris CaSO₄·½H₂O.
- Acids turn blue litmus red; pH below 7 is acidic, above 7 basic.
- Mercury is liquid at room temperature; sodium and potassium are stored under kerosene.
Biology
- The cell is the structural unit; mitochondria are the powerhouse, chloroplasts carry out photosynthesis.
- Deficiency diseases: vitamin A night blindness, B1 beriberi, C scurvy, D rickets; iodine causes goitre, iron anaemia.
Worked example
A car covers 60 km at 40 km/h and another 60 km at 60 km/h. Find the average speed. Times taken: 60/40 = 1.5 h and 60/60 = 1 h. Total 120 km in 2.5 h gives 48 km/h. Averaging 40 and 60 to get 50 is wrong, because equal distances at unequal speeds require the harmonic mean, not the arithmetic mean.
Traps
- Mass (kg, constant) versus weight (newton, changes with gravity).
- Sound travels fastest in solids, not in air.
- Universal donor is O-negative, universal recipient AB-positive.