CBSE
Assertion: Nuclei having mass number about 60 are most stable.
Reason: When two or more light nuclei are combined into a heavier nucleus, then the binding energy per nucleon will increase.
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
What is the ratio of Bohr magnetron to the nuclear magnetron?
mp/me
1
If the half lives of a radioactive element for and β decay are 4 years and 12 years respectively, the ratio of its initial activity and that after 12 years will be
6.25 %
12.5 %
25 %
50 %
A nucleus of mass number 220 decays by decay. The energy released in the reaction is 5 MeV. The kinetic energy of an -particle is
MeV
MeV
MeV
MeV
A radioactive nucleus is being produced at a constant rate per second. Its decay constant is λ. If N0 are the number of nuclei at time t = 0, then the maximum number of nuclei possible are
N0 +
N0
+ N0
Two radioactive substances A and 8 have decay constants 5A and A respectively. At I =0, they have the same number of nuclei. The ratio of number of nuclei of A to those of 8 will be (1/e2 ) after a time
4λ
2λ
Assertion: It is very easy to detect neutrino in nature.
Reason: It has high affinity to interact with matter.
If both assertion and reason are true and reason is the correct explanation of assertion.
If both asertion and reason are true and reason is not correct explanation of assertion.
If assertion is true but reason is false.
If both assertion and reason are false.
The intensity of gamma radiation from a given source is I. On passing through 36 mm of lead, it is reduced to l/8. The thickness of lead which will reduce the intensity to l/2 will be
18 mm
12 mm
6 mm
9 mm
Assertion: It is desirable to slow down fast moving neutrons to sustain controlled chain reactions.
Reason: Slow moving neutrons efficiently collides with U235.
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 assertion and reason are false.
N1 atoms of a radioactive element emit N2 beta particles per second. The decay constant of the element is ( m s-1 )
N1/N2
N2/N1
N1 ( ln2 )
N2 ( ln2 )