General Science
What this domain tests
Class-10 level physics, chemistry and biology: units and measurement, motion, light, electricity, acids and bases, common compounds, cell biology, nutrition and disease. Questions are factual and formula-light, but they demand exactness - one wrong subscript or unit loses the mark.
Core rules
- SI units: force newton (kg·m/s²), pressure pascal, work and energy joule, power watt, frequency hertz, charge coulomb.
- Common compounds: baking soda NaHCO₃, washing soda Na₂CO₃·10H₂O, quicklime CaO, slaked lime Ca(OH)₂, plaster of Paris CaSO₄·½H₂O, blue vitriol CuSO₄·5H₂O.
- Deficiency map: vitamin A–night blindness, B1–beriberi, C–scurvy, D–rickets, iodine–goitre, iron–anaemia.
- Electricity: V = IR, P = VI; current stays constant in series, voltage stays constant in parallel.
Worked example
A solution of pH 3 and one of pH 5 are compared. Which is more acidic, and by what factor? pH is the negative logarithm of hydrogen-ion concentration, so [H⁺] = 10^(–pH). For pH 3, [H⁺] = 10⁻³ mol/L; for pH 5, [H⁺] = 10⁻⁵ mol/L. Ratio = 10⁻³ ÷ 10⁻⁵ = 100. So the pH 3 solution is 100 times more acidic. Check: one pH unit means a tenfold change, so two units mean 10² = 100.
Traps that cost marks
- Mass vs weight: weight changes with gravity, mass does not.
- Atomic number (protons) vs mass number (protons + neutrons).
- Viruses are not treated as ordinary cells; they reproduce only inside a host.
- The claim that sound travels faster in air than in water is false - it is faster in solids and liquids.