General Science
General Science covers Physics, Chemistry and Biology at roughly Class 6–10 level, usually applied to everyday situations, the human body, health and energy.
Physics
- SI units: force in newton, work in joule, power in watt, pressure in pascal, frequency in hertz.
- Newton's second law: F = ma; speed of light is about 3 × 10⁸ m/s.
- Ohm's law V = IR; resistances add in series and reduce in parallel.
Chemistry
- Atomic number equals the number of protons; mass number equals protons plus neutrons.
- pH below 7 is acidic, 7 neutral, above 7 basic; acids turn blue litmus red.
- Lime water test: Ca(OH)₂ + CO₂ → CaCO₃ + H₂O.
- Know common formulae: NaCl, CaO, H₂SO₄, NaOH, CO₂.
Biology
- Vitamin deficiencies: A - night blindness; B1 - beriberi; C - scurvy; D - rickets; K - poor clotting.
- Blood group AB is the universal recipient, O the universal donor.
- Photosynthesis: 6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂, occurring in chloroplasts with chlorophyll.
Worked example
Why does lime water turn milky when carbon dioxide is passed through it? Reasoning: CO₂ reacts with calcium hydroxide to form calcium carbonate, an insoluble white solid whose particles scatter light, so the liquid looks milky. Passing excess CO₂ converts the carbonate into soluble calcium bicarbonate and the milkiness disappears.
Traps
- Confusing atomic number (protons) with mass number (protons + neutrons).
- Mixing up vitamin–deficiency pairs, especially C/scurvy and D/rickets.
- Saying current is the same in every parallel branch; voltage is equal, current divides.
- Ignoring units when a numerical answer is asked.