General Science: Physics, Chemistry and Biology Basics
Core topics
Physics: SI units, motion, Newton's laws, work–power–energy, sound, reflection and refraction, Ohm's law and simple circuits, magnetic effects of current. Chemistry: atomic structure, periodic table, acids–bases–salts and pH, metals and non-metals, everyday compounds. Biology: cell structure, plant and human systems (digestive, respiratory, circulatory, excretory), vitamins and deficiency diseases, disease-causing agents, and broad classification of living organisms.
Traps that cost marks
Memorise deficiency pairs exactly: vitamin C → scurvy, vitamin D → rickets, vitamin A → night blindness, iodine → goitre. Keep units straight: force in newton, pressure in pascal, power in watt. Dengue, polio and chickenpox are viral; typhoid and tuberculosis are bacterial. Know the formulas of common compounds: baking soda is NaHCO3, washing soda is Na2CO3·10H2O, quicklime is CaO. Do not confuse mass with weight, or speed with velocity.
Rule of thumb
Ohm's law gives V = IR; electrical power is P = VI = I²R.
Worked example
A 12 V supply across a 4 Ω resistor carries I = V/R = 3 A, and dissipates P = VI = 3 × 12 = 36 W.