A last-week revision sheet for everyday science. Read every row as a “cause → effect” pair; UPSC often reverses one side.
Light
| Observation | Principle |
|---|
| Blue sky, red sunset, red danger signals | Scattering (red scattered least) |
| White clouds | Large droplets scatter all colours equally |
| Twinkling stars, early sunrise | Atmospheric refraction |
| Optical fibre, diamond sparkle | Total internal reflection |
| Rainbow | Refraction + dispersion + internal reflection |
| Soap-bubble colours | Interference |
| Beam in a dusty room | Tyndall effect |
| Eye defect | Lens |
|---|
| Myopia | Concave |
| Hypermetropia | Convex |
| Presbyopia | Bifocal |
| Astigmatism | Cylindrical |
Sound and Heat
| Fact | Detail |
|---|
| Medium | Sound cannot travel in a vacuum; fastest in solids |
| Audible range | 20 Hz – 20 kHz; infrasound below, ultrasound above |
| Echo | Reflecting surface at least about 17 m away |
| Water | Densest at about 4 °C; ice floats |
| Pressure cooker | Raises boiling point |
| High altitude | Lower pressure, lower boiling point |
| Thermos flask | Vacuum stops conduction and convection; silvering cuts radiation |
Household Chemistry
| Compound | Formula |
|---|
| Baking soda | NaHCO₃ |
| Washing soda | Na₂CO₃·10H₂O |
| Bleaching powder | CaOCl₂ |
| Plaster of Paris | CaSO₄·½H₂O |
| Gypsum | CaSO₄·2H₂O |
| Slaked lime | Ca(OH)₂ |
| Fuel | Main constituent |
|---|
| LPG | Butane + propane (ethyl mercaptan added for smell) |
| CNG | Methane |
| Biogas | Methane + carbon dioxide |
High-yield facts
- pH 7 neutral; blood about 7.4; acid rain below 5.6; tooth enamel corrodes below about 5.5.
- Rusting needs oxygen and water; galvanisation = zinc coating.
- Nitrogen in chip packets prevents rancidity.
- Detergents work in hard water; soaps form scum.
- Raman effect — 28 February 1928 (National Science Day); Nobel 1930.
Nutrition and Health
| Vitamin | Deficiency |
|---|
| A | Night blindness |
| B1 | Beriberi |
| B3 | Pellagra |
| B12 | Pernicious anaemia |
| C | Scurvy |
| D | Rickets / osteomalacia |
| K | Bleeding (poor clotting) |
| Disease | Pathogen | Vector |
|---|
| Malaria | Plasmodium (protozoan) | Female Anopheles |
| Dengue, chikungunya, Zika | Viruses | Aedes aegypti |
| Filariasis | Wuchereria (worm) | Culex |
| Japanese encephalitis | Virus | Culex |
| Kala-azar | Leishmania (protozoan) | Sandfly |
| Plague | Yersinia pestis (bacterium) | Rat flea |
| Item | Fact |
|---|
| Blood groups | O universal donor; AB universal recipient |
| HIV | Attacks helper T (CD4) cells |
| Penicillin | Fleming, 1928 |
| AMR | National Action Plan 2017; Red Line campaign 2016 |
| NFHS-5 (2019–21) | Stunting 35.5% (under-5); anaemia 57.0% (women 15–49) |
| Polio-free | Certified 27 March 2014 |
Traps
- Red is scattered least, not most.
- Plaster of Paris is the hemihydrate, gypsum the dihydrate.
- The mosquito is the vector, not the cause, of malaria.
- Antibiotics do not act on viruses.
- Vitamin C is water-soluble.
Advertisement