General Science and Mathematics
What this domain tests
This section tests school-level science and quantitative aptitude: physics units and motion, basic chemistry and biology, arithmetic, algebra, geometry, mensuration, trigonometry, and statistics. For an electronics exam, formula accuracy and unit handling matter more than long derivations.
Core concepts
- Physics: speed = distance/time; force = mass × acceleration; work = force × distance; power = work/time. SI units include metre, kilogram, second, ampere, kelvin, mole, and candela.
- Chemistry: atomic number equals protons; mass number equals protons plus neutrons. pH below 7 is acidic; above 7 is basic. Biology: the cell is the basic unit; mitochondria are associated with energy release.
- Arithmetic: percentage, ratio, average, profit/loss, simple and compound interest, time-speed-distance, and time-work. Profit% is calculated on cost price unless stated otherwise.
- Algebra: linear equations, identities, and quadratic factors. Geometry: angle sum, circle properties, and Pythagoras. Mensuration: area and volume formulas. Statistics: mean, median, mode.
Worked example
A shopkeeper marks an item 25% above cost and allows a 10% discount. Take cost price = 100. Marked price = 125. Selling price = 125 × 0.90 = 112.5. Profit = 12.5, so profit percentage = 12.5% on cost.
Traps
Apply BODMAS correctly. A 10% discount is taken on the marked price, not on cost. Simple interest is not compound interest. Convert units before substituting; for example, km/h to m/s requires multiplying by 5/18.
Key points
- Profit% is normally on cost price.
- Discount is on marked price.
- km/h × 5/18 = m/s.
- Atomic number = protons; mass number = protons + neutrons.
- Mean = sum of values / number of values.