Questions and answers for exam Preparation

MCQs

Total Questions : 150 | Page 5 of 15 pages

Question 41. Cyclotron is a device which

detects and analyses the spectrum of light emitted by stars
accelerates subatomic particles using combined electric and magnetic fields
detects the cyclic variation in the intensity of electromagnetic radiation emitted from stars
measures the intensity of X-rays

Discuss Question

Answer: Option B. -> accelerates subatomic particles using combined electric and magnetic fields
:
B
Option:(b)

Question 42. Raindrops are spherical due to

viscosity of water
surface tension
continuous evaporation
air friction

Discuss Question

Answer: Option B. -> surface tension
:
B
Option:(b)

Question 43. The following processes take place during the launch of a rocket.
What is the proper order in which they take place?
1.Rocket fuel is burnt
2.Gases are produced
3.Rocket moves in the forward direction
4.Gases come out with momentum in backward direction

1, 2, 4, 3
1, 2. 3,4
4, 1, 2, 3
1, 4, 3, 2

Discuss Question

Answer: Option A. -> 1, 2, 4, 3
:
A
Option:(a)

Question 44. The surface of water in a pond remains cool even on a hot day because

water evaporates at the surface and evaporation causes cooling
the heat absorbed at the surface is transmitted downwards
water in a contact with the bottom of the pond becomes cool and rises to the surface due to convention
none of these

Discuss Question

Answer: Option A. -> water evaporates at the surface and evaporation causes cooling
:
A
Option:(a)

Question 45. During summer, we feel comfortable under a fan because it

throws cool air on us
sets the air in motion, thereby increasing the evaporation of sweat
produces convection currents
produces air which carries heat away from the body

Discuss Question

Answer: Option B. -> sets the air in motion, thereby increasing the evaporation of sweat
:
B
Option:(b)

Question 46. Consider the following statements:
In a nuclear reactor, self-sustained chain reaction is possible, because
1.more neutrons are released in each of the fission reactions.
2.the neutrons immediately take part in the fission process.
3.the fast neutrons are slowed down by graphite.
4.every neutron released in the fission reaction initiates further fission.Which of these statements are correct?

1, 2 and 3
1 and 3
2 and 4
2, 3 and 4

Discuss Question

Answer: Option A. -> 1, 2 and 3
:
A
Option:(a)

Question 47. A fuse is used in mains electric supply as a safety device. Which one of the following statements about the fuse is correct?

It is connected in parallel with the main switch
It is made mainly from silver alloys
It must have a low melting point
It must have a very high resistance

Discuss Question

Answer: Option C. -> It must have a low melting point
:
C
Option:(c)

Question 48. Which one of the following does a TV remote control unit use to operate a TV set?

Light waves
Sound waves
Microwaves
Radio waves

Discuss Question

Answer: Option D. -> Radio waves
:
D
Option:(d)

Question 49. When light waves pass from air to glass, the variables affected are

wavelength, frequency and velocity
velocity and frequency
wavelength and frequency
wavelength and velocity

Discuss Question

Answer: Option D. -> wavelength and velocity
:
D
Option:(d)

Question 50. Consider the following features of newer models of motor cars
1.Radial tyres
2.Streamlined body
3.Multipoint fuel injection
4.Catalytic converter with exhaustWhich of these features make the new models of motor cars more fuel efficient?