Q1. The bats can fly in the dark because (a) They have a better vision in the dark (b) The light startles them (c) They produce ultrasonics (d) None of the above Answer: (c) They produce ultrasonics Explanation: Bats use echolocation, emitting ultrasonic sound waves that bounce off objects and return to them. This allows …
Q1. Which of the following metals is used in the electromagnets ? (a) Soft iron (b) Stainless steel (c) Cobalt (d) Copper (UPSC Prelims 1979) Answer: (a) Soft iron Explanation: Soft iron is used in electromagnets because it has high magnetic permeability and low retentivity, allowing it to quickly gain and lose magnetism. This makes …
Q1. A ball bounces higher at high altitudes than in plains. This is because (a) The pressure on higher altitudes is lower than that in plains (b) Downward pull due to gravity is less at higher altitudes (c) The rarefied air offers less resistance to the ball (d) You become more energetic at hills, so …
Q49. An ordinary clock loses time in summer. This is because (a) The length of the pendulum increases and time period increases (b) The length of the pendulum increases and time period decreases (c) The length of the pendulum decreases and time period increases (d) The length of the pendulum decreases and time period decreases …
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) …
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 …
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 …
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, …
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 …