Atoms have different atomic numbers as well as different mass numbers but have the same number of neutrons is called:
1. | isotopes | 2. | isobars |
3. | isotones | 4. | isodiaphers |
The binding energies of the nuclei A and B are respectively. Three atoms of the element B fuse to give one atom of element A and an energy Q is released. Then and Q are related as:
1.
2.
3.
4.
A free neutron decays into a proton, an electron and:
1. A beta particle.
2. An alpha particle.
3. An antineutrino.
4. A neutrino.
In a radioactive sample the fraction of initial number of radioactive nuclei, which remains undecayed after n mean lives is:
1.
2.
3.
4.
The activity of a radioactive sample is measured as 9750 counts/min at t = 0 and as 975 counts/min at t = 5 min. The decay constant is approximately:
1. 0.922/min
2. 0.691/min
3. 0.461/min
4. 0.230/min
Fission of nuclei is possible because the binding energy per nucleon in them [2005]
1. increases with mass number at high mass number
2. decreases with mass number at high mass
3. increases with mass number at low mass numbers
4. decreases with mass number at low mass number
A nucleus emits one and two particles. The resulting nucleus is
1.
2.
3.
4. None of these
The half-life period of a radioactive substance is 6 h. If after 24 h, activity is 0.01 Ci, what was the initial activity?
1. 0.04 Ci
2. 0.08 Ci
3. 0.24 Ci
4. 0.16 Ci
The radius of a nucleus of a mass number A is directly proportional to [MH CET 1999; AMU (En.) 2001; UPSEAT 2004; DUMET 2010]
1.
2. A
3.
4.
The radioactivity of a sample is at a time and at time . If the mean life of the specimen is T, the number of atoms that have disintegrated in the time interval of is:
1.
2.
3.
4.