UPSC | National Defence Academy (NDA) | Section A, B, C | Exam II 2019

Part B

(Section : Physics, Chemistry & General Science)

Below are given the question from section A, B And C covering topics from Physics, Chemistry and General Science asked in Part B of the Question Paper 2019.

51. A thin disc and a thin ring, both have mass M and radius R. Both rotate about axes through their center of mass and are perpendicular to their surfaces at the same angular velocity. Which of the following is true ?
(a) The ring has higher kinetic energy
(b) The disc has higher kinetic energy
(c) The ring and the disc have the same kinetic energy
(d) Kinetic energies of both the bodies are zero since they are not in linear motion

52. Let there be an object having some chemicals in it. It starts moving with a uniform velocity v and a chemical reaction starts happening. In this case, which of the following statement/s is/are correct ?
1. Chemical reactions happening in the system cannot change the velocity v of the center of mass of the object.
2. Chemical reactions happening in the system cannot change kinetic energy of the particles inside with respect to the center of mass of object.
Select the correct answer using the code given below:
(a) 1 only
(b) 2 only
(c) Both 1 and 2
(d) Neither 1 nor 2

53. In which of the following phenomena do heat waves travel along a straight line with the speed of light ?
(a) Thermal conduction
(b) Thermal convection
(c) Thermal radiation
(d) Both, thermal conduction and radiation

54. Which one of the following statements regarding Ohm’s law is not correct?
(a) Ohm’s law is · an assumption that current through a conductor is always directly proportional to the potential difference applied to it.
(b) A conducting device obeys Ohm’s law when the resistance of a device is independent of magnitude and polarity of applied potential difference.
(c) A conducting material obeys Ohm’s law when the resistance of material is independent of the magnitude and direction of applied electric field.
(d) All homogeneous materials obey Ohm’s law irrespective of whether the field is
within range or strong.

55. When a ball bounces off the ground, which of the following changes suddenly ? (Assume no loss of energy to the floor)
(a) Its speed
(b) Its momentum
(c) Its kinetic energy
(d) Its potential energy

56. Which one of the following compounds does not exhibit a different oxidation number of the same element ?
(a) Pb304
(b) Fe304
(c) Fe203
(d) Mn304

57. Which one of the following statements about glass is not correct ?
(a) Glass is often said to be a supercooled liquid.
(b) Glass has no definite melting point.
(c) Soda glass i s harder than pyrex glass.
(d) Boron is present in pyrex glass.

58. Which one of t he following statements is correct?
(a) Both boiling and evaporation are surface phenomena.
(b) Boiling is a surface phenomenon, but evaporation is a bulk phenomenon.
(c) Both boiling and evaporation are bulk phenomena.
(d) Boiling is a bulk phenomenon, but evaporation is a surface phenomenon.

59. Which one of the following statements about diamond and graphite is not correct?
(a) Diamond has a tetrahedral structure, whereas graphite has a hexagonal planar structure.
(b) Both physical and chemical properties of diamond and graphite are different.
(c) Graphite’is soft but diamond is hard.
(d) Graphite is a good conductor of electricity while diamond is not.

60. The raw materials used for the manufacture of Portland cement are
(a) Lime, silica and sulphur dioxide
(b) Lime, silica and carbon dioxide
(c) Lime, silica and alumina
(d) Lime, silica and boric acid

61. Which one of the following statements about water is not true ?
(a) Hydrogen bonds are present in liquid water.
(b) Water has a high boiling point.
(c) Water has a high heat of fusion.
(d) Water is a non-polar molecule.

62. A sample of soft soap  contains
(a) Caesium
(b) Potassium
(c) Calcium
(d) Magnesium

63. If an object .moves at a non-zero constant acceleration for a certain interval of time, then the distance it covers in that time
(a) depends on its initial velocity.
(b) is independent of its initial velocity.
(c) increases linearly with time.
(d) depends on its initial displacement.

64. A solid disc and a solid sphere have the same mass and same radius. Which one has the higher moment of inertia about its centre of mass?
(a) The disc
(b) The sphere
(c) Both have the same moment of inertia
(d) The information provided is not sufficient to answer the question

65. Two substances of densities \rho_{1} and \rho_{2} are mixed in equal volume and their relative density is 4. When they are mixed in equal masses, relative density is 3. The values of \rho_{1} and \rho_{2} respectively are
(a) 6, 2
(b) 3, 5
(c) 12,4
(d) 9, 3

66. A car starts from Bengaluru, goes 50 km in a straight line towards south, immediately turns around and returns to Bengaluru. The time taken for this round trip is 2 hours. The magnitude of the average velocity of the car for this round trip
(a) is 0.
(b) is 50 km/hr.
(c) is 25 km/hr.
(d) cannot be calculated without knowing acceleration.

67. “The sum of emfs and potential differences around a closed loop equals zero” is a consequence of
(a) Ohm’s law.
(b) Conservation of charge.
(c) Conservation of momentum.
(d) Conservation of energy.

68. A student measures certain lengths using a meter scale having least count equal to 1 mm. Which one of the following measurements is more precise ?
(a) 0·50 mm
(b) 29·07 cm
(c) 0·925 m
(d) 910 mm

69. If the work done on the system or by the system· is zero, which one of the following statements for a gas kept at a certain temperature is correct ?
(a) Change in internal energy of the system is equal to flow of heat in or out of the system.
(b) Change in internal energy of the system is less than heat transferred.
(c) Change in internal energy of the system is more than the h eat flow.
(d) Cannot be determined.

70. Consider the following part of an electric circuit:
The total electrical resistance in the given part of the electric circuit is
(a ) \large{\frac{15}{8}} ohm
(b) \large{\frac{15}{7}} ohm
(c) 15 ohm
(d) \large{\frac{17}{3}} ohm

71. Which one of the following statements regarding lenses is not correct ?
(a) A convex lens produces both real and virtual images
(b) A concave lens produces both real and virtual images
(c) A convex lens can produce images equal, greater and smaller than size of the object
(d) A concave lens can produce images equal, greater and smaller than size of the object

72. 10 g of ice at – l0°C is mixed with 10 g of water at 0 °C. The amount of heat required to raise the temperature of mixture to 10°C is
(a) 400 cal
(b) 550 cal
(c) 1050 cal
(d) 1200 cal

73. Which one of the following does not represent the salt, Calcium carbonate ?
(a) Lime water
(b) Limestone
(c) Chalk
(d) Marble

74. Soaps clean surfaces on the principle based on
(a) Viscosity
(b) Floatation
(c) Elasticity
(d) Surface tension

75. Which one of the following substances is not a mixture?
(a) Tin
(b) Sea water
(c) Soil
(d) Air

76. Which one of the following is termed as ‘Dry ice’ ?
(a) Ice present in ice-cream
(b) Solid water at Antarctica
(c) Solid state of carbon dioxide
(d) Solid water of ionosphere

77. Net movement of water from a dilute to a concentrated solution through a selectively permeable membrane is called
(a) Diffusion
(b) Dispersion
(c) Osmosis
(d) Absorption

78. Blood is a type of
(a) Epithelial tissue
(b) Muscular tissue
(c) Nervous tissue
(d) Connective tissue

79. Mitochondria are able to produce their own
(a) Nucleus
(b) Proteins
(c) Chloroplasts
(d) Digestive enzymes

80. Which one of the following statements is correct ?
(a) Xylem consists of tracheids, vessels, xylem parenchyma and xylem fibres.
(b) Flexibility in plants is due to sclerenchyma.
(c) Parenchyma have no intercellular spaces.
(d) Xylem consists of sieve plate, sieve tube and companion cells.

81. Who among the following popularized the use of embryological characters in taxonomy ?
(a) Carl Linnaeus
(b) Panchanan Maheshwari
(c) Birbal Sahni
(d) Bentham and Hooker

82. Water is heated with a coil of resistance R connected to domestic supply. The rise of temperature of water will depend on
1. Supply voltage.
2. Current passing through the coil.
3. Time for which voltage is supplied.
Select the correct answer from among the following:
(a) 1, 2 and 3
(b) 1 and 2 only
(c) 1 only
(d) 2 and 3 only

83. A pendulum clock is lifted to a height where the gravitational acceleration has a certain value g. Another pendulum clock of same length but of double the mass of the bob is lifted to another height where the gravitational acceleration is g/2. The time period of the second pendulum would be: (in terms of period T of the first pendulum)
(a) \sqrt{2} T
(b) \frac{1}{\sqrt{2}} T
(c) 2 \sqrt{2} T
(d) T

84. The loudness of sound depends upon the
(a) velocity of sound waves in the medium.
(b) amplitude of the sound waves.
(c) frequency of t he sound waves.
(d) frequency and velocity of the sound waves.

85. Two bodies of mass M each are placed R distance apart. In another system, two bodies of mass 2M each are placed \frac{R}{2} distance apart. If F be the gravitational force between the bodies in the first system, then the gravitational force between the bodies in the second system will be
(a) 16 F
(b) 1 F
(c) 4 F
(d) None of t he above

86. Light rays move in straight lines. But through an optical fibre, they can move in any type of zigzag path because
(a) the holes through the fibre are extremely fine.
(b) light rays are absorbed at the entry end and relieved at the exit end of the fibre.
(c) scattering of light occurs inside the fibre.
(d) successive total internal reflections occur as a ray moves through the fibre.

87. Which one of the following statements regarding cathode rays is not correct ?
(a) Cathode ray particles are electrons.
(b) Cathode ray particles start from anode and move towards cathode.
(c) In the absence of electrical and magnetic  fields, cathode rays travel in straight lines.
(d) Television picture tubes are cathode ray tubes.

88. A very large volume of hydrogen can be accommodated by making
(a) non-metallic hydrides.
(b) hydrogen peroxide.
(c) non-stoichiometric hydrides.
(d) alkali metal hydrides.

89. Which one of the following is not a monatomic element?
(a) Copper
(b) Helium
(c) Iodine
(d) Barium

90. Which one of the following represents the correct order of electron releasing tendency of metals?
(a) Zn > Cu > Ag
(b) Ag > Cu > Zn
(c) Cu > Zn > Ag
(d) Cu > Ag > Zn

91. Which one of the following is the major constituent of biogas ?
(a) Carbon dioxide
(b) Nitrous oxide
(c) Methane
(d) Oxygen

92. Thyroid gland produces a hormone called “Thyroxine” which
(a) controls blood glucose levels.
(b) controls ovulation .
(c) controls metabolic rate.
(d) maintains pregnancy.

93. Which one of the following is a bacterium that causes disease in the human body ?
(a) Varicella zoster
(b) Trypanosoma gambiense
(c) Salmonella typhi
(d) Plasmodium falciparum

94. Which one of the following statements regarding viruses is not true ?
(a) Viruses need living cells to reproduce.
(b) All viruses are parasites.
(c) Viruses can synthesize their food through photosynthesis.
(d) Viruses are similar to chemical substances outside the host.

95. Which one of t he following diseases may be caused by the deficiency of vitamin C ?
(a) Rickets
(b) Rabies
(c) Hepatitis
(d) Scurvy

96. Compared to audible sound waves, ultrasound waves have
(a) higher speed.
(b) higher frequency.
(c) longer wavelength.
(d) both higher speed and frequency.

97. A rigid body of mass 2 kg is dropped from a stationary balloon kept at a height of 50 m from the ground. The speed of the body when it just touches the ground and the total energy when it is dropped from the balloon are respectively (acceleration due to gravity = 9·8 m/s2 )
(a ) 980 m.s-1 and 980 J
(b) \sqrt{980} m.s-1 and \sqrt{980} J
(c) 980 m.s-1 and \sqrt{980} J
(d) \sqrt{980} m.s-1 and 980 J

98. The temperature of a place on one sunny day is 113 in Fahrenheit scale. The Kelvin scale reading of this temperature will be
(a) 318 K
(b) 45 K
(c) 62·8 K
(d) 335·8 K

99. Radiations coming from the Sun are mostly in the form of
(a ) light only.
(b) light and long wavelength infrared.
(c) light and short wavelength infrared.
(d) both short and long wavelength infrared.

100. Which of the following are the characteristics of electromagnetic waves ?
1. They are elastic waves.
2. They can also move in vacuum.
3. They have electric and magnetic components which are mutually perpendicular.
4. They move with a speed equal to 3 lakh meters per second.
Select the correct answer u sing the code given below :
(a) 1, 2, 3 and 4
(b) 1, 2 and 4 only
(c) 2 and 3 only
(d) 3 and 4 only

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