MCQOPTIONS
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MCQOPTIONS
This section includes 10 Mcqs, each offering curated multiple-choice questions to sharpen your Physics knowledge and support exam preparation. Choose a topic below to get started.
| 1. |
A freshly prepared radioactive source of half-time 2h emits radiation of intensity which is 64 times the permissible safe level. Minimum time after which it would be possible to work safely with this source is which of the following? |
| A. | 6 h |
| B. | 12 h |
| C. | 24 h |
| D. | 20 h |
| Answer» C. 24 h | |
| 2. |
What will happen in a time of 7 hours, if a radioactive substance has an average life of 7 hours? |
| A. | Half of the active nuclei decay |
| B. | Less half of the active nuclei decay |
| C. | More than half of the active nuclei decay |
| D. | All active nuclei decay |
| Answer» D. All active nuclei decay | |
| 3. |
What is the half-time of a radioactive sample (in minutes), if its mean life is 200 s? |
| A. | 0.69 min |
| B. | 2 min |
| C. | 2.57 min |
| D. | 2.31 min |
| Answer» E. | |
| 4. |
Which will be the unknown nucleus formed when 22Ne10 decays into two α-particles and an unknown nucleus? |
| A. | Fluorine |
| B. | Carbon |
| C. | Neon |
| D. | Oxygen |
| Answer» C. Neon | |
| 5. |
Emission of β-rays in radioactive decay results in the change of either mass or charge. |
| A. | True |
| B. | False |
| Answer» C. | |
| 6. |
A 300-day old radioactive substance shows an activity of 5000 dps, 150 days later its activity becomes 2500 dps. What was its initial activity? |
| A. | 25000 dps |
| B. | 20000 dps |
| C. | 32000 dps |
| D. | 5000 dps |
| Answer» C. 32000 dps | |
| 7. |
Find the probability that the nucleus of 87Ra221 undergoes decay after three half-lives, if its a radioactive substance which has a half-life of 6 days. |
| A. | \(\frac {1}{6}\) |
| B. | \(\frac {3}{2}\) |
| C. | \(\frac {5}{6}\) |
| D. | \(\frac {1}{2}\) |
| Answer» D. \(\frac {1}{2}\) | |
| 8. |
The electron emitted in β – radiation originates from where? |
| A. | Inner orbits of atoms |
| B. | Free electrons existing in nuclei |
| C. | The decay of a neutron in nuclei |
| D. | Photon escaping from the nucleus |
| Answer» D. Photon escaping from the nucleus | |
| 9. |
Which of the following substances cannot be emitted by radioactive substances during their decay? |
| A. | Protons |
| B. | Neutrinos |
| C. | Helium nuclei |
| D. | Electrons |
| Answer» B. Neutrinos | |
| 10. |
Radioactive material decays by simultaneous emission of two particles with respective half-lives 1620 and 810 years. The time, in years, after which one-fourth of the material remains? |
| A. | 1080 |
| B. | 2430 |
| C. | 3240 |
| D. | 4860 |
| Answer» B. 2430 | |