Subject-Specific Section (Physics / Chemistry / Biology / Computer Science / Commerce / Arts)
What this section tests
Questions drawn from the first-year core syllabus of your NAT stream, mixing recall with short numericals. Physics: units and dimensions, Newton's laws, work–energy, optics, current electricity. Chemistry: periodicity, bonding, the mole concept and stoichiometry, equilibrium, functional groups. Biology: cell structure, genetics and Punnett squares, human physiology, ecology. Computer Science: number systems, logic gates, data structures, programming constructs, basic databases and networking. Commerce: the accounting equation, journal and ledger, demand and supply, forms of business organisation. Arts: dates, key figures, terminology, and cause–effect in historical events.
Concepts to master
Know your formulae and definitions cold, including units and sign conventions. In numericals, list the given quantities first. In definitional items, match the function, not just the term.
Traps that repeat
- Unit mismatch in numerical answers (N versus kg, J versus kJ).
- Sign conventions in lenses and in thermodynamics.
- Confusing atomic number with mass number; confusing moles with molecules.
- A distractor using the right word with the wrong relation or definition.
- Missing a NOT or EXCEPT in the stem.
- Choosing a familiar-sounding option without checking the numerical.
Rule of thumb
Solve from the definition or formula first and use recall only to check. For any multi-step numerical, write given → formula → substitute with units → answer with units. If the answer's units are wrong, the reasoning is wrong, whatever the number.
Worked example
How many oxygen atoms are in 44 g of CO₂? Molar mass is 44 g/mol, so this is 1 mol of CO₂, giving 1 mol of molecules but 2 mol of oxygen atoms - about 1.204 × 10²⁴ atoms. The trap is stopping at 6.022 × 10²³.