1. | \({}_{34}^{74}\mathrm{Se}, {}_{31}^{71}\mathrm{Ca}\) | 2. | \({}_{42}^{92}\mathrm{Mo}, {}_{40}^{92}\mathrm{Zr}\) |
3. | \({}_{38}^{81}\mathrm{Sr}, {}_{38}^{86}\mathrm{Sr}\) | 4. | \({}_{20}^{40}\mathrm{Ca}, {}_{16}^{32}\mathrm{S}\) |
1. | \(4x+4y\) | 2. | \(4x-4y\) |
3. | \(4y-4x\) | 4. | \(y-x\) |
Fusion reaction takes place at a higher temperature because:
1. | atoms get ionized at high temperatures. |
2. | kinetic energy is high enough to overcome the Coulomb repulsion between nuclei. |
3. | molecules break up at a high temperature. |
4. | nuclei break up at a high temperature. |
1. | \({ }_{7}^{14} \mathrm{N}\) | 2. | \({ }_{5}^{13} \mathrm{B}\) |
3. | \({ }_{7}^{13} \mathrm{N}\) | 4. | \({ }_{6}^{13} \mathrm{C}\) |
If a proton and anti-proton come close to each other and annihilate, how much energy will be released?
1. | \(1.5 \times10^{-10}~\text{J}\) | 2. | \(3 \times10^{-10}~\text{J}\) |
3. | \(4.5 \times10^{-10}~\text{J}\) | 4. | None of these |
1. | \(6\) and \(8\) | 2. | \(6\) and \(6\) |
3. | \(8\) and \(8\) | 4. | \(8\) and \(6\) |
A radioactive sample has a half-life of 1770 years. At some instant, 20% of the sample has decayed. If taking this instant as , it is found that at , 20% of the sample is left, then is:
1. 1770 years
2. 885 years
3. 2655 years
4. 3540 years
If the half-life of a radioactive substance is 10 hours, then its mean life is:
1. 14.4 h
2. 7.2 h
3. 20 h
4. 6.93 h
1. | Electron and antineutrino |
2. | Positron and antineutrino |
3. | Positron and neutrino |
4. | Electron and positron |