CBSE
Multiple Choice QuestionsAssertion: Heavy water preferred ever ordinary water as a moderator in reactors.
Reason: Heavy water, used for slowing down the neutrons, has lesser absorption probability
of neutrons than ordinary water.
If both assertion and reason are true and reason is the correct explanation of assertion
If both assertion and reason are true but reason is not the correct explanation of assertion
If assertion is true but reason is false
If both assertion and reason are false
Nuclear fusion is possible
only between light nuclei
only between heavy nuclei
between both light and heavy nuclei
only between nuclei which are stable against β-decay
A radioactive substance decays to 1/16th of its initial activity in 40 days. The half-life of the radioactive substance expressed in days is
2.5
5
10
20
Two parallel beams of positrons moving in the same direction will
repel each other
will not interact with each other
attract each other
be deflected normal to the plane containing the two beams
A neutron makes a head-on elastic collision with a stationary deuteron. The fractional energy loss of the neutron in the collision is
16/81
8/9
8/27
2/3
Assertion: Energy is released in nuclear fission.
Reason: Total binding energy of the fission fragments is larger than the total binding energy of the parent nucleus.
If both assertion and reason are true and reason is the correct explanation of assertion
If both assertion and reason are true but reason is not the correct explanation of assertion
If assertion is true but reason is false
If both assertion and reason is false
The dependence of binding energy per nucleon, BA on the mass number A, is represented by
Carbon dating is best suited for determining the age of fossils if their age in years is of the order of
108
104
104
106
Assertion: 90Sr from the radioactive fall out from a nuclear bomb ends up in the bones of human beings through the milk consumed by them. It causes impairment of the production of red blood cells.
Reason: The energies β-particles emitted in the decay of 90Sr damage the bone marrow.
If both assertion and reason are true and reason is the correct explanation of assertion
If both assertion and reason are but reason is not the correct explanation of assertion
If asserion and reason is false
If both assertion and reason are false
A proton is about 1840 times heavier than an electron. When it is accelerated by a potential difference of 1 kV, its kinetic energy will be
1840 keV
1/1840 keV
1 keV
920 keV
