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UPSC Prelims PYQ | Light
Q1. When light enters a closed room through a small hole in the door, the image of an outside building appears as inverted on the opposite wall. This is because (a) The hole acts as a convex lens (b) Light takes curvature at the edges of the hole (c) Of rectilinear propagation of light (d) …
UPSC Prelims PYQ | Law of Gas
Q1. One litre of cold air weighs heavier than the dry air (1 Lit) because of the (a) Increased number of collisions between the molecules (b) Increased number of molecules at low temperature (c) Greater energy of molecules at high temperature (d) Lower energy of molecules at high temperature Answer: (b) Increased number of molecules …
UPSC Prelims PYQ | Horticulture
Q1. The two branches of a plant give two different fruits : tomatoes and brinjals. This can be explained (a) By hybridisation (b) By grafting one with the other (c) By nature’s freak (d) By (a) or (c) mentioned above (UPSC Prelims 1979) Answer: (b) By grafting one with the other Explanation: Grafting is a …
UPSC Prelims PYQ | Chemistry of Water
Q1. Permanent hardness of water cannot be removed by (a) Boiling (b) Adding caustic soda (c) Distillation (d) Adding soda Answer: (a) Boiling Explanation: Permanent hardness is caused by dissolved salts of calcium and magnesium, such as chlorides and sulphates, which do not precipitate on boiling. Unlike temporary hardness, which can be removed by heating, …
UPSC Prelims PYQ | Fluid Mechanics
Q1. A body partially floats in wafer when (a) The volume of the displaced liquid is equal to the volume of the body (b) The volume of the displaced liquid is greater than the volume of the body (c) The weight of the displaced water is equal to the weight of the body (d) The …
UPSC Prelims PYQ | Precipitation
Q1. Less dew is formed on cloudy nights because (a) Clouds absorb the falling dew (b) Clouds scatter moisture (c) In cloudy nights the radiation takes place very slowly (d) In cloudy nights the radiation takes place very quickly (UPSC Prelims 1979) Answer: (c) In cloudy nights the radiation takes place very slowly Explanation: On …
UPSC Prelims PYQ | Disease and Vectors
Q1. In India it is found recently that incidence of Malaria is increasing because (a) The mosquitoes have become DDT resistant (b) Of poverty in villages (c) Of poor sanitary conditions (d) On account of increase in population it has become impossible to maintain cleanliness everywhere (UPSC Prelims 1979) Answer: (a) The mosquitoes have become …
UPSC Prelims PYQ | Life Cycle
Q1. After hatching by the hen, the young chicks come out of eggs within (a) One week (b) Two weeks (c) Three weeks (d) Four weeks (UPSC Prelims 1979) Answer: (c) Three weeks Explanation: The incubation period for hen eggs is typically around 21 days, or three weeks, during which the embryo develops inside the …
UPSC Prelims PYQ | Ecology
Q1. Stripes on the back of the animals are the indication of (a) Mating habit (b) Food habit (c) Cave dwelling (d) Matching of skin colour with surroundings (UPSC Prelims, 1979) Answer: (d) Matching of skin colour with surroundings Explanation: Stripes and patterns on animals serve as camouflage, helping them blend with their environment. This …