General Science and Basic Mathematics
Science: the predictable topics
- Physics: SI units, motion and Newton's laws, work, energy and power, light and sound, electricity and Ohm's law, simple machines.
- Chemistry: atomic structure, periodic table basics, acids, bases and salts with pH, metals and non-metals, and common compounds: baking soda NaHCO3, washing soda Na2CO3.10H2O, plaster of Paris CaSO4.1/2H2O.
- Biology: cell structure, human digestive and circulatory systems, vitamins and deficiency diseases, photosynthesis, classification, and disease vectors.
Mathematics: the scoring core
Concentrate on percentage, ratio and proportion, average, profit and loss, simple and compound interest, time-speed-distance, time and work, LCM and HCF, mensuration and data interpretation.
Worked example (percentage)
'A panchayat's MGNREGA wage bill rises from Rs 4,00,000 to Rs 5,00,000. Find the percentage increase.' Reasoning: the increase is Rs 1,00,000; percentage increase = increase divided by original, times 100 = 1,00,000 divided by 4,00,000, times 100 = 25 per cent. The Rs 1,00,000 is 20 per cent of the new figure, and using the new figure as the base is the standard error.
Worked example (science)
'Why does lemon juice turn blue litmus red?' Reasoning: lemon juice contains citric acid, and acids turn blue litmus red while bases turn red litmus blue. Answer: because it is acidic.
Traps
- Mixing SI and non-SI units, such as newton and dyne.
- Forgetting that simple and compound interest are equal for the first year only.
- Applying a percentage to the wrong base, as shown above.
- Deficiency confusion: scurvy from vitamin C, rickets from vitamin D, night blindness from vitamin A, beri-beri from vitamin B1.