GENERAL SCIENCE – PHYSICS- 71 TO 80

71. At what temperature will the density of water be maximum?
a) 0 oC
b) 32 oC
c) – 4 oC
d) 4 oC

Answer is: d)4 oC

72).Persistence of vision is the principle behind?
a) Camera
b) spectroscope
c) Cinema
d) Periscope

Answer is: c) Cinema

73. RADAR is used for

A.locating submerged submarines
B.receiving a signals in a radio receiver
C.locating geostationary satellites
D.detecting and locating the position of objects such as aeroplanes

Answer: Option D- detecting and locating the position of objects such as aeroplanes

74. Sound of frequency below 20 Hz is called

A.audio sounds
B.infrasonic
C.ultrasonic
D.supersonics

Answer: Option B- infrasonic

75. Light from the laser is________.
a) Monochromatic
b) Composite
c) Dispersed light
d) Incoherent

Answer is: a) Monochromatic

76. On a clean glass plate a drop of water spreads to form a thin layer whereas a drop of mercury remains almost spherical because

A.mercury is a metal
B.density of mercury is greater than that of water
C.cohesion of mercury is greater than its adhesion with glass
D.cohesion of water is greater than its adhesion with glass

Answer: Option C- cohesion of mercury is greater than its adhesion with glass

77. Suitable impurities are added to a semiconductor depending on its use. This is done in order to

A.increase its life
B.enable it to withstand higher voltages
C.increase its electrical conductivity
D.increase its electrical resistivity

Answer: Option C- increase its electrical conductivity

78. Stars twinkle because

A.the intensity of light emitted by them changes with time
B.the distance of the stars from the earth changes with time
C.the refractive index of the different layers of the earth’s atmosphere changes continuously, consequently the position of the image of a start changes with time
D.the light from the star is scattered by the dust particles and air molecules in the earth’s atmosphere

Answer: Option C- the refractive index of the different layers of the earth’s atmosphere changes continuously, consequently the position of the image of a start changes with time

79. Moment of inertia is

A.vector
B.scalar
C.phasor
D.tensor

Answer: Option D-tensor

80. Of the following natural phenomena, tell which one known in Sanskrit as ‘deer’s thirst’?

A.Rainbow
B.Earthshine
C.Halo
D.Mirage

Answer: Option D- Mirage

Explanation:

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