In a mean life of radioactive sample :
about of substance disintegrates
about of substance disintegrates
about 90% of the substance disintegrates
almost all the substance disintegrates
If the half-life of any sample of a radioactive substance is 4 days, then the fraction of the sample will remain undecayed after 2 days, will be
For the stability of any nucleus:
binding energy per nucleon will be more
binding energy per nucleon will be less
no. of electrons will be more
none of these
Nuclear fusion is common to the pairs :
thermonuclear reactor, uranium based nuclear reactor
energy production in sun, uranium-based nuclear reactor
energy production in sun, hydrogen bomb
the disintegration of heavy nuclei, hydrogen bomb
A radioactive substance containing N atoms emits n - particles per second. Half-life of the substance is :
sec
sec
sec
sec
In a radioactive decay,
92U238 X ZYA
The values of Z and A
92 , 236
88 , 230
90 , 130
88 , 234
B.
88 , 230
After emission of - particle, the atomic number of new element is reduced by 2 unit and the atomic mass is reduced by 4 unit. Therefore, the new element after emission of - particle is 90X234. Again by emission of one more - paricle from 90X234 nucleus, new element is 88230.
In a sample of radioactive substance, what percentage decays in one mean life time?
69.3 %
63 %
50 %
36 %
Number of nuclei of a radioactive substance at time t = O are 2000 and 1800 at time t = 2s. Number of nuclei left after t = 6s is
1442
1554
1652
1458
92U238 on absorbing a neutron goes over to 92U239. This nucleus emits an electron to go over to neptunium which on further emitting an electron goes over to plutonium. The resulting plutonium can be expressed as
94Pu239
90Pu219
93Pu240
92Pu240
The radius of nucleus of silver (atomic number = 47) is 3.4 x 10-14 m. The electric potential on the surface of nucleus is (e = 1.6 x 10-19 C)
1.99 x 106 V
2.9 x 106 V
4.99 × 106 V
0.99 x 106 V