General Science
Domain 2 - General Science
Physics, Chemistry and Biology at Class 6–10 level, leaning heavily on everyday applications and human biology.
Physics
- SI units: force in newton (N), pressure in pascal (Pa), energy in joule (J), power in watt (W), frequency in hertz (Hz).
- Newton's laws; F = ma; momentum = mv.
- Ohm's law V = IR; series resistances add, parallel reciprocals add.
- Plane mirror image: virtual, erect, laterally inverted, same size; focal length is infinite.
- Light ≈ 3 × 10^8 m/s; sound ≈ 343 m/s in air, faster in solids.
Chemistry
- Atomic number = protons; mass number = protons + neutrons.
- pH below 7 acid, 7 neutral, above 7 base.
- Common names: baking soda NaHCO3, washing soda Na2CO3·10H2O, quicklime CaO, slaked lime Ca(OH)2, plaster of Paris CaSO4·½H2O, blue vitriol CuSO4·5H2O.
Biology
- Deficiency: vitamin A - night blindness; B1 - beriberi; C - scurvy; D - rickets; K - poor clotting.
- Vectors: Anopheles - malaria; Aedes - dengue; housefly - typhoid.
- Blood groups A, B, AB, O; O negative is the universal donor.
Worked example
A car travels at 72 km/h for 20 minutes. Find the distance. 72 km/h = 72 × 5/18 = 20 m/s. 20 min = 1200 s. Distance = 20 × 1200 = 24,000 m = 24 km.
Traps that cost marks
- Swapping atomic number with atomic mass.
- Assuming every mirror forms a real image - a convex mirror always gives a virtual, diminished image.
- Writing kilogram as the SI unit of weight; it is newton.
- Confusing the cause of a disease with its vector.