NDA (I) Exam 2021 – General Aptitude Test Part – B (Answer Key)

71. Consider the following statements about Light year :
1. Light year is a unit for measurement of very large distances.
2. Light year is a unit for measurement of very large time intervals.
3. Light year is a unit for measurement of intensity of light.
Which of the statements given above is/are correct?
(a) 1, 2 and 3
(b) 2 and 3 only
(c) 1 and 2 only
(d) 1 only

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72. Which one of the following regarding density of water at atmospheric pressure is correct ?
(a) Density of water at 4°C is 1000 kg/m³.
(b) Density of water at 0°C is 1000 kg/m³.
(c) Density of water at 0°C is 100 kg/m³.
(d) Density of water at 4°C is 10 kg/m³.

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73. Which of the following pairs of physical phenomenon and the discoverer is/are correctly matched ?
1. James Chadwick : Photoelectric effect
2. Albert Einstein : Neutron
3. Marie Curie : Radium
Select the correct answer using the code given below :
(a) 1, 2 and 3
(b) 1 and 2 only
(c) 2 and 3 only
(d) 3 only

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74. LED (a semiconductor device) is an abbreviation that stands for
(a) Licence for Energy Detector.
(b) Light Energy Device.
(c) Light Emitting Diode.
(d) Lost Energy Detector.

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75. The statement “friction force is a contact force while magnetic force is a non-contact force” is
(a) always true.
(b) true only at 0°C.
(c) a false statement.
(d) either true or false depending upon the temperature of the surroundings.

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76. Which one of the following is the chemical formula of Hypobromous acid ?
(a) HBrO₄
(b) HOBr
(c) HBr
(d) HBrO₃

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77. The composition of gases in exosphere is
(a) Helium and Hydrogen.
(b) Neon and Oxygen.
(c) Neon and Hydrogen.
(d) Helium and Neon.

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78. Which one of the following is not used as a raw material in the manufacture of glass ?
(a) Soda
(b) Alumina
(c) Borax
(d) Gypsum

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79. In electrolytic refining of copper, the electrolyte is a solution of
(a) acidified copper chloride.
(b) acidified copper sulphate.
(c) potassium chloride.
(d) sodium sulphate.

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80. Solder is an alloy of
(a) Cu and Sn.
(b) Fe and Zn.
(c) Pb and Sn.
(d) Ag and Zn.

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81. Which one of the following statements about dihydrogen (H₂) is not correct ?
(a) H₂ is lighter than air and insoluble in het water.
(b) H₂ is inert at room temperature due to high H – H bond dissociation enthalpy.
(c) H₂ reacts with alkali metals at high temperature to yield metal hydrides.
(d) A mixture of NO₂ and H₂ is known as Syngas.

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82. Which of the following sets of elements has the same valency?
(a) Na, Mg, Ca
(b) Na, Mg, Al
(c) Mg, Ca, K
(d) Mg, Ca, Ba

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83. Which one of the following is the lowest possible temperature ?
(a) 0° Celsius
(b) – 073° Celsius
(c) – 173° Celsius
(d) – 273° Celsius

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84. Numerically two thermometers, one in Fahrenheit scale and another in Celsius scale shall read same at
(a) — 40°
(b) 0°
(c) — 273°
(d) 100°

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85. The image we see in plane mirror is
(a) real and thus can be photographed.
(b) virtual and nearer than the object.
(c) virtual and is laterally inverted.
(d) real but cannot be photographed.

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86. If human blood is placed in a 2% detergent solution, what will happen to the RBC ?
(a) The RBC will shrink.
(b) The RBC will swell and become turgid.
(c) The RBC will swell and burst.
(d) The RBC will lyse.

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87. The major source of vitamins and minerals for vegetarians is
(a) black gram and wheat.
(b) rice and mustard.
(c) vegetables and fruits.
(d) soya bean and milk.

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88. If a ray of light enters from a rarer medium to a denser medium at zero angle of incidence, it would
(a) reflect back.
(b) go straight.
(c) turn towards right.
(d) bend at 45°.

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89. Mirage is an illustration of
(a) only dispersion of light.
(b) only reflection of light.
(c) only total internal reflection of light.
(d) both refraction and total internal reflection of light.

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90. Common salt (NaCl) is not used as a raw material for preparation of which one of the following compounds ?
(a) Bleaching powder
(b) Baking soda
(c) Plaster of Paris
(d) Washing soda

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