SOLVED PAPER 2020 (CDS) (II) (General Studies)

Total Questions: 120

101. Which of the following lenses will bend the light rays through largest angle?

Correct Answer: (b) Lens with power + 2.5 D
Solution:The power of a lens is defined as its ability to bend the light rays falling on it. So, the lens with more power will bend the light rays through largest angle.

∴ The lens with + 2 5. D will bend the light rays through largest angle.

102. A luminous object is placed at a distance of 40 cm from a converging lens of focal length 25 cm. The image obtained in the screen is

Correct Answer: (c) inverted and magnified
Solution:Given,

103. When a light ray enters into glass medium from water at an angle of incidence 0°, what would be the angle of refraction?

Correct Answer: (c) 0°
Solution:

When a light ray enters into glass medium from water at angle of incidence 0°, it will fall normally on the glass medium.

If the incident ray falls normally to the surface of glass medium, then there will be no bending of the light ray. It goes straight without any deviation

∴ Angle of refraction = 0°

104. Which one of the following phenomena verifies the fact that light travels much faster than sound?

Correct Answer: (c)Thunderstorm
Solution:In case of a thunderstorm, the lightning is seen first and then we hear the thunder after some time. This is because light travels with speed 3 × 10⁸ ms⁻¹ in air while sound travels at a speed of 340 ms⁻¹ in air. This phenomenon proves the fact that light travels much faster than sound.

105. Which one of the following combinations of source and screen would produce sharpest shadow of an opaque object?

Correct Answer: (c) A point source and a transparent screen
Solution:To form the sharpest shadow of an opaque object, a point source and a transparent screen are required.

106. Which one among the following is a non-conventional source of energy?

Correct Answer: (d) Solar energy
Solution:Non-conventional sources of energy are those sources of energy which are being produced continuously in nature and are inexhaustible. Amongst the given options, solar energy is a non-conventional source of energy.

107. Which one of the following statements about phloem is correct?

Correct Answer: (d) Phloem gives support to the plant.
Solution:Option (b) is correct as the phloem is the means by which the products of photosynthesis are transported to non-photosynthetic parts of the plant, such as the roots and to developing leaves, nectaries, fruits and seeds.

Other statements can be corrected as

  • Xylem transports water and minerals.
  • Phloem is a complex tissue.
  • Primary function of phloem is transport of sugars not support.

108. Mature sclerenchyma cells have

Correct Answer: (d) lignified wall and are dead
Solution:Mature Sclerenchyma consists of long, narrow cells with thick and lignified cell walls having a few or numerous pits. They are usually dead and without protoplasts.

109. In human beings, the chromosomes that determine birth of a normal female child are

Correct Answer: (a) one X chromosome from mother and one X chromosome from father
Solution:The chromosome number of a normal female is 44 + XX. It has one X-chromosomes which comes from mother and one X-chromosome which comes from father.

Thus option ‘A’ is correct

  • Fusion of two X from mother and one X from father will lead to birth of superfemale (XXX).
  • Fusion of one X-chromosome and one Y-chromosome from father and one X-chromosome from mother will lead to birth of a child with Klienfelter syndrome (XXY).

110. Antibiotic such as penicillin blocks

Correct Answer: (a) cell wall formation in bacteria
Solution:Antibiotics such as penicillin kills bacteria by inhibiting or blocking the proteins which cross-link peptidoglycans in the cell wall. When these bacterium divides in the presence of penicillin, it cannot fill in the ‘holes’ left in its cell wall.