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
D.
Number of nuclei remained after time t can be written as
N = No e-λt
where No is initial number of nuclei of both the substances.
N1 = No e-5λt ....... (i)
and N2 = No e-λt ...... (ii)
Dividing Eqn (i) by Eqn (ii), we obtain
But we have given
Comparing the powers we get
2 = 4λt
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
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