Fission of nuclei is possible because the binding energy per nucleon in them
increases with mass number at high mass numbers
decreases with mass number at high mass numbers
increases with mass number at low mass numbers
decreases with mass number at low mass numbers
In any fission process the ratio is
less than 1
greater than 1
greater than 1
depends on the mass of parent nucleus
In radioactive decay process, the negatively charged emitted -particles are
the electrons present inside the nucleus
the electrons produced as a result of the decay of neutrons inside the nucleus
the electrons produced as a result of collisions between atoms
the electrons orbiting around the nucleus
Two radioactive substances A and B have decay constants 5 λ and λ respectively. At t = 0 they have the same number of nuclei. The ratio of number of nuclei of A to those of B will be after a time interval
4λ
2λ
If Mo is the mass of an oxygen isotope 8O17 , MP and Mn are the masses of a proton and a neutron, respectively, the nuclear binding energy of the isotope is
( Mo - 8 MP ) c2
( Mo - 8 MP - 9 Mc ) c2
Mo C2
(Mo - 17 Mn ) c2
Hydrogen bomb is based upon
fission
fusion
chemical reaction
transmutation
B.
fusion
The working of hydrogen bomb is based on nuclear fusion. But for the process of nuclear fusion, a very high temperature (≈ 107 K) and a very high pressure is required, hence to construct a hydrogen bomb, first atom bomb is constructed.
The atom bomb is then covered from all sides by an enclosure of a compound of heavy hydrogen (deuteron) such as lithium hydride. First the atom bomb is exploded which produces such a high temperature and pressure that deuteron nuclei get fused and a huge amount of energy is released.
The operation of a nuclear reactor is said to be critical, if the multiplication factor (k) has a value
1
1.5
2.1
2.5
Half-lives of two radioactive substances A and B are respectively 20 min and 40 min. Initially the samples of A and B have equal number of nuclei. After 80 min the ratio of remaining number of A and B nuclei is
1 : 16
4 : 1
1 : 4
1 : 1
The half-life of a radio-isotope is 4h. If initial mass of the isotope was 200 g, then mass remaining after 24 h will be
1.042 g
2.084 g
3.125 g
4.167 g
If 82U238 emits 8 - particles and 6 β - particles, then the resulting nucleus is
82U206
82Pb206
82U210
82U214