71. Stars which appear single to the naked eye but are double when seen through a telescope are
A. novas and supernovas
B. binaries
C. asteroids
D. quasars
✅ The correct answer is option B.
Physics MCQs
72. Light travels at the fastest speed in
A. glass
B. water
C. hydrogen
D. vacuum
✅ The correct answer is option D.
73. Sound produced at a point is heard by a person after 5 second, while the same sound is heard by another person after 6 seconds. If the speed of sound is 300 m/s, what could be the maximum and minimum distances between the two persons?
A. 1.8 km, 0.15 km
B. 2.2 km, 0.20 km
C. 2.8 km, 0.25 km
D. 3.3 km, 0.30 km
✅ The correct answer is option D.
74. Railway tracks are banked on curves
A. necessary centrifugal force may be obtained from the horizontal component weight of the train
B. to avoid frictional force between the tracks and wheels
C. necessary centripetal force may be obtained from the horizontal component of the weight of the train
D. the train may not fly off in the opposite direction
✅ The correct answer is option C.
75. Sound waves in air are
A. transverse
B. longitudinal
C. electromagnetic
D. polarised
✅ The correct answer is option B.
77. Find the maximum velocity for the overturn of a car moving on a circular track of radius 100 m. The co-efficient of friction between the road and tyre is 0.2
A. 0.14 m/s
B. 140 m/s
C. 1.4 km/s
D. 14 m/s
✅ The correct answer is option D.
78. Mach number is used in connection with the speed of
A. sound
B. aircraft
C. spacecraft
D. ships
✅ The correct answer is option B.
79. Mica is used in electrical appliances such as electric iron because mica is
A. a good conductor of heat but a bad conductor of electricity
B. a bad conductor of heat but a good conductor of electricity
C. a good conductor of heat as well as electricity
D. a bad conductor of heat as well as electricity
✅ The correct answer is option A.