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Science & Technology

923 questions asked in UPSC Prelims.

2000 · Q103Science & TechnologyPhysicsmoderate

Assertion (A): A man standing on a completely frictionless surface can propel himself by whistling. Reason (R): If no external force acts on a system, its momentum cannot change.

  1. (a)Both A and R are true, and R is the correct explanation of A
  2. (b)Both A and R are true, but R is not a correct explanation of A
  3. (c)A is true, but R is false
  4. (d)A is false, but R is true
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Official answer(a) Both A and R are true, and R is the correct explanation of A

2000 · Q104Science & TechnologyPhysicsmoderate

Assertion (A): In a motion picture, usually 24 frames are projected every second over the whole length of the film. Reason (R): An image formed on the retina of eye persists for about 0.1 s after the removal of stimulus.

  1. (a)Both A and R are true, and R is the correct explanation of A
  2. (b)Both A and R are true, but R is not a correct explanation of A
  3. (c)A is true, but R is false
  4. (d)A is false, but R is true
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Official answer(a) Both A and R are true, and R is the correct explanation of A

2000 · Q105Science & TechnologyPhysicsmoderate

Assertion (A): Small glass beads fixed on traffic signals glow brightly when light falls upon them. Reason (R): Light is totally reflected when the angle of incidence exceeds a certain critical value and light travelling in a denser medium is reflected back into a rarer medium.

  1. (a)Both A and R are true, and R is the correct explanation of A
  2. (b)Both A and R are true, but R is not a correct explanation of A
  3. (c)A is true, but R is false
  4. (d)A is false, but R is true
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Official answer(a) Both A and R are true, and R is the correct explanation of A

2000 · Q114Science & TechnologyPhysicsmoderate

Assertion (A): Large cold storage plants use ammonia as refrigerant while domestic refrigerators use chlorofluorocarbons. Reason (R): Ammonia can be liquified at ambient temperatures at low pressures.

  1. (a)Both A and R are true, and R is the correct explanation of A
  2. (b)Both A and R are true, but R is not a correct explanation of A
  3. (c)A is true, but R is false
  4. (d)A is false, but R is true
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Official answer(a) Both A and R are true, and R is the correct explanation of A

2000 · Q117Science & TechnologyHealth & Diseasesmoderate

Match List I (Diseases) with List II (Types of disease) and select the correct answer using the codes given below the Lists: List I I. Haemophilia II. Diabetes III. Diabetes IV. Ringworm List II A) Deficiency disease B) Genetic disease C) Hormonal disorder D) Fungal infection Codes:

  1. (a)I-B, II-C, III-D, IV-A
  2. (b)I-B, II-C, III-A, IV-D
  3. (c)I-C, II-B, III-A, IV-D
  4. (d)I-C, II-B, III-D, IV-A
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Official answer(b) I-B, II-C, III-A, IV-D