General Science (Physics, Chemistry, Biology)
General Science tests school-level concepts that support engineering study: measurement, motion, electricity, matter, acids and bases, cell biology, human physiology, and plant processes. The best preparation is to know definitions, units, and one-line explanations of everyday phenomena.
Core rules
- SI base units include metre, kilogram, second, ampere, kelvin, mole, and candela.
- Newton's second law: force = mass × acceleration; weight is a force, mass is not.
- Ohm's law: V = IR for a metallic conductor at constant temperature.
- pH = −log10[H+]; a change of one pH unit means a tenfold change in hydrogen-ion concentration.
- Acids turn blue litmus red; bases turn red litmus blue; strong acids and bases dissociate almost completely in water.
- The cell is the basic unit of life; photosynthesis converts light energy into chemical energy in chloroplasts.
Worked example
Find the pH of 0.01 M HCl. HCl is a strong acid, so [H+] ≈ 0.01 = 10⁻² mol/L. pH = −log10(10⁻²) = 2. The reasoning depends on complete dissociation; for a weak acid, the dissociation constant would be needed.
Biology links
Revise the digestive system, blood components, vitamins and deficiency diseases, and plant tissues. A common question links a deficiency to a symptom, such as vitamin C with scurvy or iron with anaemia.
Traps that cost marks
Treating pH as a linear scale; confusing mass with weight; using Ohm's law for non-ohmic devices without qualification; assuming plants only photosynthesise and do not respire; confusing a strong acid with a concentrated acid.
Key points
- pH is logarithmic; one unit equals a tenfold change.
- Weight is force; mass is quantity of matter.
- Strong acid means complete dissociation, not high concentration.
- Vitamin C deficiency causes scurvy; iron deficiency causes anaemia.