Q. No.The half-life of a radioactive nucleus is 50 days. The time interval between the time when of it has decayed and the time when of it had decayed is:
1. 30 days
2. 50 days
3. 60 days
4. 15 days
Two radioactive nuclei P and Q, in a given sample decay into a stable nucleus R. At time t=0, the number of P species are and that of Q is Half-life of P(for conversion to R) is 1 min whereas that of Q is 2 min. Initially there are no nuclei of R present in the sample. When number of nuclei of P and Q are equal, the number of nuclei of R present in the sample would be:
1.
2.
3.
4.
The decay constant of a radio isotope is If and are its activities at times and respectively, the number of nuclei which have decayed during the time
1.
2.
3.
4.
The mass of an -particle is:
| 1. | less than the sum of masses of two protons and two neutrons. |
| 2. | equal to the mass of four protons. |
| 3. | equal to the mass of four neutrons. |
| 4. | equal to the sum of masses of two protons and two neutrons. |
1. Electron
2. Positron
3. Proton
4. Neutron
1. \(3.2\times 10^{-13}~\text{J}\)
2. \(1.6\times 10^{-13}~\text{J}\)
3. \(4.8\times 10^{-13}~\text{J}\)
4. \(6.4\times 10^{-13}~\text{J}\)
Fission of nuclei is possible because the binding energy per nucleon in them:
| 1. | increases with mass number at high mass numbers. |
| 2. | decreases with mass number at high mass numbers. |
| 3. | increases with mass number at low mass numbers. |
| 4. | decreases with mass number at low mass numbers. |
1. Nitrogen
2. Carbon
3. Boron
4. Oxygen
1. \(4\alpha~\text{and}~2\beta\)
2. \(6\alpha~\text{and}~4\beta\)
3. \(8\alpha~\text{and}~24\beta\)
4. \(4\alpha~\text{and}~16\beta\)
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