General Science
General Science tests basic physics, chemistry and biology at Class 10 level, with application to everyday phenomena and engineering contexts. Expect units, laws, human physiology, plant processes, acids-bases and electricity.
Core rules and concepts
- SI units: length metre, mass kilogram, time second, force newton, work joule, power watt, pressure pascal.
- Motion: speed = distance/time; velocity includes direction; acceleration = change in velocity/time. Newton's laws explain inertia, F=ma and action-reaction.
- Electricity: Ohm's law V=IR; power P=VI=I²R=V²/R. Household wiring is parallel; the earth wire is a safety connection.
- Chemistry: pH below 7 is acidic, 7 neutral, above 7 basic; acids react with bases to form salt and water.
- Biology: photosynthesis uses CO2, water and light to make glucose and O2; xylem transports water, phloem transports food.
Worked example
Convert 72 km/h to m/s. Multiply by 1000/3600, which equals 5/18. So 72 × 5/18 = 20 m/s. If this speed is maintained for 15 s, distance = speed × time = 20 × 15 = 300 m. The reasoning depends on converting units before applying the formula.
Traps
Mass is not weight; weight = mg and changes with gravity. Speed is scalar, velocity is vector. In pH, a change of 1 unit is a tenfold change in hydrogen-ion concentration. Do not say plants respire only at night; respiration is continuous. In circuits, adding resistors in parallel lowers equivalent resistance.