46.  Nichrome wire is used in an electric heater because

a

  It has high resistance

b

 It has high melting point

c

 For all of the above reasons

d

 It can resist a current upto approx 5 amperes

Answer & Explanation
Answer : Option C

47.  Mirage is due to

a

  magnetic disturbances in the atmosphere

b

 depletion of ozone layer in the atmosphere

c

 equal heating of different parts of the atmosphere

d

 unequal heating of different parts of the atmosphere

Answer & Explanation
Answer : Option D

48.  Out of the following pairs, choose the pair in which the physical quantities do not have identical dimension?

a

  Impulse and moment of force

b

 Pressure and Young's modules

c

 Planck's constant and Angular momentum

d

 Force and rate of change of linear momentum

Answer & Explanation
Answer : Option A

49.  An ice cube is floating on the surface of water: How will the water level be affected by melting of this ice cube?

a

  Water level will go down

b

 Water level will be raised

c

 Water level will remain the same

d

 Water level will first rise up then it will go down

Answer & Explanation
Answer : Option C

50.  Planets do not twinkle because

a

  they are nearer to earth and hence we receive a greater amount of light and, therefore minor variations in the intensity are not noticeable

b

 they are very far away from the earth resulting in decrease in intensity of light

c

 their distance from the earth does not change with time

d

 they emit light of a constant intensity

Answer & Explanation
Answer : Option A

51.  Light travels at the fastest speed in

a

  glass

b

 water

c

 vacuum

d

 hydrogen

Answer & Explanation
Answer : Option C

52.  One should not connect a number of electrical appliances to the same power socket because

a

  the appliance will not get full voltage

b

 this can damage the electrical meter

c

 this can damage the appliances due to overloading

d

 this can damage the domestic wiring due to overloading

Answer & Explanation
Answer : Option D

53.  Solar cell converts

a

  Solar energy into electrical energy

b

 Electrical energy into light energy

c

 Sound energy into electrical energy

d

 Electrical energy into mechanical energy

Answer & Explanation
Answer : Option A

54.  Force of attraction between the molecules of same substance is called

a

  Adhesive force

b

 Cohensive force

c

 Surface tension

d

 None of above

Answer & Explanation
Answer : Option B

55.  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

 1.4 km/s

c

 14 m/s

d

 140 m/s

Answer & Explanation
Answer : Option C

56.  Moment of inertia is

a

  vector

b

 scalar

c

 tensor

d

 phasor

Answer & Explanation
Answer : Option C

57.  Metals are good conductors of electricity because

a

  they contain free electrons

b

 the atoms are lightly packed

c

 they have high melting point

d

 All of the above

Answer & Explanation
Answer : Option A

58.  It takes much longer to cook food in the hills than in the plains, because

a

  in the hills the atmospheric density is low and therefore a lot of heat is lost to the atmosphere

b

 in the hills the humidity is high and therefore a lot of heat is absorbed by the atmosphere leaving very little heat for cooking

c

 due to low atmospheric pressure on the hills, the water boils at a temperature higher than 100◦C and therefore water takes longer to boil

d

 in the hills the atmospheric pressure is lower than that in the plains and therefore water boils at a temperature lower than 100◦C causing an increase in cooking time

Answer & Explanation
Answer : Option D

59.  Radiocarbon is produced in the atmosphere as a result of

a

  lightning discharge in atmosphere

b

 action of ultraviolet light from the sun on atmospheric oxygen

c

 collision between fast neutrons and nitrogen nuclei present in the atmosphere

d

 action of solar radiations particularly cosmic rays on carbon dioxide present in the atmosphere

Answer & Explanation
Answer : Option C

60.  When water is heated from 0◦ Celsius to 100◦Celsius, the volume of water

a

  Increase gradually

b

 Degrease gradually

c

 First increase, then decrease

d

 First decrease, then increase

Answer & Explanation
Answer : Option D
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