English (Part – B) (NDA SOLVED PAPER 2020 – II) (101 to 150)

Total Questions: 50

41. The Sun appears reddish during sunrise and sunset. The phenomenon in optics which is responsible for this appearance of the Sun is

Correct Answer: (c) Scattering
Solution:

The Sun appears reddish during sunrise and sunset due to scattering of light.

42. A lens has a power of +2·0 Dioptre. Which one of the following statements about the lens is true?

Correct Answer: (c) The lens is convex and has a focal length of 0.5 m
Solution:

43. At nearly 70°C, sodium bicarbonate shows the property of gradually decomposing, which makes it usable in bakery products. The product of decomposition responsible for this use of sodium bicarbonate is

Correct Answer: (a) Carbon dioxide
Solution:

44. Number of molecules of water of crystallisation in copper sulphate, sodium carbonate and gypsum are

Correct Answer: (a) 5, 10 and 2 respectively
Solution:

Number of molecules of water of crystallisation of copper sulphate, sodium carbonate and Gypsum are 5, 10 and 2 respectively.
Complete chemical formula are as follows

45. Which one of the following is the correct sequence of change in colours when a turmeric stain on white clothes is scrubbed by soap and then washed with water?

Correct Answer: (b) Yellow-reddish brown-yellow
Solution:

When a turmeric stain appear on white clothes it becomes reddish brown when it come in contact with soap, which is basic in nature it turns yellow again when the cloth is washed with plenty of water

46. Which one of the following statements regarding bleaching powder and DDT is correct?

Correct Answer: (c) Both contain chlorine
Solution:

Both bleaching powder (CaOCl₂) and Dichloro Diphenyl Tricholoroethane (DDT) contain chlorine. Bleaching powder is inorganic compound, but DDT is an organic halogen compound. structures are as follows

47. Which one of the following is the best example of desiccant?

Correct Answer: (a) Silica gel
Solution:

Silica gel is the best example of desiccant. It is hygroscopic in nature. It absorbs water from the surrounding.

48. Which one of the following was the first mineral acid discovered?

Correct Answer: (a) Sulphuric acid
Solution:

Sulphuric acid (H₂SO₄) was the first mineral acid discovered

49. The refractive index of fused quartz is 1·46 and that of sapphire is 1·77. If Vq is the speed of light in quartz and Vₛ is the speed of light in sapphire, then which one of the following relations is correct?

Correct Answer: (a)
Solution:

50. In case of a concave mirror, if an object is kept between principal focus F and pole P of the mirror, then which one of the following statements about the image is not correct?

Correct Answer: (c) The image will be formed at infinity
Solution:

If the object is placed between F and P of concave mirror, the image is formed behind the mirror. The image formed is virtual, erect and magnified