Q. No.The half-life of a radioactive substance is 30 minutes. The time (in minutes) taken between 40% decay and 85% decay of the same radioactive substance is:
1. 15
2. 30
3. 45
4. 60
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Reason (R): Electrostatic force of repulsion between two protons reduces net nuclear forces between them.
A radioactive nucleus \(X\) decays to a stable nucleus \(Y.\) Then, the graph of the rate of formation of \(Y\) against time \(t\) will be:
| 1. |  |
2. |  |
| 3. |  |
4. |  |
A nucleus of uranium decays at rest into nuclei of thorium and helium. Then:
| 1. | The nucleus helium has more kinetic energy than the thorium nucleus |
| 2. | The helium nucleus has less momentum than the thorium nucleus |
| 3. | The helium nucleus has more momentum than the thorium nucleus |
| 4. | The helium nucleus has less kinetic energy than the thorium nucleus |
Fission of nuclei is possible because the binding energy per nucleon in them-
1. Decreases with mass number at low mass numbers
2. Increases with mass number at low mass numbers
3. Decreases with mass number at high mass numbers
4. Increases with mass number at high mass numbers
\({ }_{\mathrm{Z}}^{\mathrm{A}} \mathrm{X} \rightarrow { }_{\mathrm{Z}+1}^{\mathrm{A}} \mathrm{Y}\rightarrow { }_{\mathrm{Z-1}}^{\mathrm{A-4}} \mathrm{B}\rightarrow { }_{\mathrm{Z-1}}^{\mathrm{A-4}} \mathrm{B}\) the particles emitted in the sequence are:
| 1. | \(\beta, \alpha, \gamma\) | 2. | \( \gamma, \beta, \alpha\) |
| 3. | \(\beta, \gamma,\alpha\) | 4. | \(\alpha,\beta, \gamma\) |
The number of beta particles emitted by a radioactive substance is twice the number of alpha particles emitted by it. The resulting daughter is an:
| 1. | isobar of a parent. | 2. | isomer of a parent. |
| 3. | isotone of a parent. | 4. | isotope of a parent. |
In the radioactive decay process, the negatively charged emitted β-particles are:
| 1. | the electrons present inside the nucleus |
| 2. | the electrons produced as a result of the decay of neutrons inside the nucleus |
| 3. | the electrons produced as a result of collisions between atoms |
| 4. | the electrons orbiting around the nucleus |
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