General Science and Health: Concepts with Public-Health Facts
The science and health portion of the Kharidar examination covers basic physics, chemistry and biology along with public-health facts that matter in Nepal. Questions are mostly conceptual and factual, with a few simple numerical items on speed, energy and units.
Core concepts
- Physics: SI units - force in newton, energy in joule, power in watt, pressure in pascal. Kinetic energy = ½mv², potential energy = mgh, Ohm's law V = IR.
- Chemistry: atomic number equals the number of protons; acids turn blue litmus red and have pH below 7; common formulas include H₂O, CO₂, NaCl and CaCO₃; hard water contains calcium and magnesium salts.
- Biology: the cell is the structural and functional unit of life; photosynthesis converts light energy into chemical energy; know the digestive, respiratory, circulatory and nervous systems at a basic level.
- Health in Nepal: routine immunisation starts with BCG and OPV-0 at birth, followed by pentavalent and PCV doses in infancy and measles-rubella at 9 and 15 months; Japanese encephalitis vaccine is given in endemic districts.
- Disease and deficiency: malaria is spread by the female Anopheles mosquito and dengue by Aedes; vitamin A deficiency causes night blindness, iron deficiency causes anaemia and iodine deficiency causes goitre.
Worked example
A 10 kg object moves at 5 m/s. Find its kinetic energy. Reasoning: KE = ½mv² = ½ × 10 × 5² = ½ × 10 × 25 = 125 J. Square the speed before multiplying, and keep mass in kilograms and speed in metres per second so the answer is in joules.
Traps that cost marks
- Confusing mass in kilograms with weight in newtons.
- Swapping the mosquito vectors of malaria and dengue.
- Mixing up vitamins and minerals for a given deficiency disease.