Modern And Space Physics, Sources Of Energy - Category Wise Question And Answer Practice Test With Solutions


Set 1

Set 2

Set 3

Question : 1

Which of the following does NOT allow harmful ultraviolet radiations from the sun to reach the earth?

a) NO2

b) CO2  

c) O2  

d) O3  

Answer: (d)

Question : 2

Television signals are

a) amplitude modulated

b) both frequency and amplitude modulated

c) frequency modulated

d) phase modulated

Answer: (b)

Question : 3 [NDA]

If an a-particle is projected normally through a uniform magnetic field, then the path of the a-particle inside the field will be

a) parabolic

b) elliptical

c) circular

d) a straight line

Answer: (c)

Question : 4

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 the statements given above are correct?

a) 1 and 3

b) 2 and 4

c) 1, 2 and 3

d) 2, 3 and 4

Answer: (c)

A nuclear reactor is a device to initiate and control a sustained nuclear chain reaction. The most common use of nuclear reactors is for the generation of electrical power and for the power in some ships.

In every fission reaction in which uranium nuclei splits up to give smaller nuclei three more neutrons are produced which further results into splitting of heavy uranium nuclei and more number of neutrons will be produced.

Thus, statement, 1 & 2 are correct.

In nuclear reactor all the neutrons produced can not take part in fission reaction, else reaction can turn out extremely violent. Thus, graphite rods are used as a control rods to slow down the speed of fast moving neutrons. Thus, statement 3 is also correct.

Question : 5

The number of atoms per unit cell in a sc, bcc and fcc system are:

a) 8, 6 and 10 respectively

b) 1, 4 and 2 respectively

c) 1, 2 and 4 respectively

d) 2, 4 and 1 respectively

Answer: (c)

Number of atoms per unit cell,

$n = {N_c}/8 + {N_f}/2 + {N_i}/1$

For scc system, $N_c = 8, N_f = 0$ and

$N_i = 2$, so n = 2

For f.c.c. system, $N_c = 8, N_f = 0$ and

$N_i = 4$, so n = 4


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