General Science
General Science questions sit at Class 10 level and reward definitions, units and everyday applications rather than theory. Expect physics on electricity and light, chemistry on formulae and pH, and biology on cells, nutrition and human systems.
Physics
- Newton's three laws; work, power, energy; conservation of energy.
- Light: laws of reflection, refraction, mirror and lens relations; real versus virtual images.
- Ohm's law V = IR; series R = R1 + R2; parallel 1/R = 1/R1 + 1/R2; power P = VI.
- Sound: frequency, amplitude, audible range 20 Hz–20 kHz.
Chemistry
- Atomic number = protons; mass number = protons + neutrons; isotopes differ in neutrons.
- Acids turn blue litmus red; pH below 7 acidic, above 7 basic, 7 neutral.
- Formulae: baking soda NaHCO3, washing soda Na2CO3·10H2O, quicklime CaO, slaked lime Ca(OH)2, plaster of Paris CaSO4·½H2O.
Biology
- Cell: mitochondria for respiration and ATP, chloroplast for photosynthesis, ribosome for protein synthesis.
- Deficiency: vitamin A night blindness, B1 beriberi, C scurvy, D rickets; iron anaemia, iodine goitre.
Worked example
Resistors of 6 Ω and 3 Ω are joined in parallel and the combination is placed in series with 4 Ω across a 12 V supply. Parallel: 1/R = 1/6 + 1/3 = 1/6 + 2/6 = 3/6, so R = 2 Ω. Series total = 2 + 4 = 6 Ω. Current I = V/R = 12/6 = 2 A.
Traps
- Mass (kg, constant) versus weight (N, changes with g).
- Swapping series and parallel formulas.
- Mixing up the site of photosynthesis with the site of respiration.