1. | \({}_{26}^{89}\mathrm{Kr}\) | 2. | \({}_{36}^{89}\mathrm{Kr}\) |
3. | \({}_{26}^{90}\mathrm{Sr}\) | 4. | \({}_{38}^{89}\mathrm{Sr}\) |
1. | \(1.5\times 10^{17}\) | 2. | \(3\times 10^{19}\) |
3. | \(1.5\times 10^{25}\) | 4. | \(3\times 10^{25}\) |
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. |
Which of the following is used as a moderator in nuclear reactors?
1. Plutonium
2. Cadmium
3. Heavy water
4. Uranium
1. | The conservation of charge |
2. | The conservation of mass |
3. | The conservation of mass energy |
4. | The conservation of momentum |
(a) | nuclear forces have short-range. |
(b) | nuclei are positively charged. |
(c) | the original nuclei must be completely ionized before fusion can take place. |
(d) | the original nuclei must first break up before combining with each other. |
1. | (a) and (c) | 2. | (a) and (d) |
3. | (b) and (d) | 4. | (a) and (b) |
The mass number of a nucleus is equal to:
1. | the number of neutrons in the nucleus. |
2. | the number of protons in the nucleus. |
3. | the number of nucleons in the nucleus. |
4. | none of them. |