Curie is a unit of
energy of gamma rays
half - life
radioactivity
intensity of gamma rays
In the nucleus of 11Na23, the number of protons, neutrons and electrons are
11, 12, 0
23, 12, 11
12, 11, 0
23, 11, 12
Which of the following statements is true for nuclear forces?
They obey the inverse square law of distance.
They obey the inverse third power law of distance.
They are short range forces.
They are equal in strength to electromagnetic forces.
The binding energy per nucleon is maximum in case of
2He4
26Fe56
56Ba141
92U235
Heavy water is used as a moderator in a nuclear reactor. The function of the moderator is
To control energy released in the reactor
To absorb neutrons and stop chain reaction
To cool the reactor
To slow down the neutrons to thermal energies
A radioactive element has half-life period 800 yr. After 6400 yr what amount will remain?
1/2
1/16
1/8
1/256
<p>The nucleus <sub>6</sub>C<sup>12</sup> absorbs an energetic neutron and emits a beta particle ( β ). The resulting nucleus is</p>
7N14
7N13
5B13
6C13
Which of the following are suitable for the fusion process?
Light nuclei
Heavy nuclei
Elements lying in the middle of periodic table
Elements lying in the middle of binding energy curve
The mass density of a nucleus varies with mass number A as
A2
A
Constant
1/A
A radioactive sample with a half-life of 1 month has the label: ‘Activity = 2 microcurie on 1 – 8 – 1991’. What would be its activity two months earlier?
1.0 microcurie
0.5 microcurie
8 microcurie
