Assertion (A): | Cobalt-60 is useful in cancer therapy. |
Reason (R): | \(\gamma\)-radiation capable of killing cancerous cells. | Cobalt-60 is a source of
1. | Both (A) and (R) are true and (R) is the correct explanation of (A). |
2. | Both (A) and (R) are true but (R) is not the correct explanation of (A). |
3. | (A) is true but (R) is false. |
4. | Both (A) and (R) are false. |
Statement-I: | The law of radioactive decay states that the number of nuclei undergoing the decay per unit time is inversely proportional to the total number of nuclei in the sample. |
Statement-II: | The half life of a radionuclide is the sum of the left time of all nuclei, divided by the initial concentration of the nuclei at time \(t=0.\) |
1. | Both Statement-I and Statement-II are correct. |
2. | Both Statement-I and Statement-II are incorrect. |
3. | Statement-I is correct but Statement-II is incorrect. |
4. | Statement-I is incorrect but Statement-II is correct. |
Assertion (A): | If high pressure is applied to a radioactive substance, rate of radioactivity does not change. |
Reason (R): | Radioactivity is a nuclear process. |
1. | Both (A) and (R) are true and (R) is the correct explanation of (A). |
2. | Both (A) and (R) are true but (R) is not the correct explanation of (A). |
3. | (A) is true but (R) is false. |
4. | Both (A) and (R) are false. |
The fraction of the original number of radioactive atoms that disintegrates (decays) during the average lifetime of a radioactive substance will be:
1. \(\frac{1}{e}\)
2. \(\frac{1}{1+e}\)
3. \(\frac{e-1}{e+1}\)
4. \(\frac{e-1}{e}\)
At some instant, the number of radioactive atoms in a sample is \(N_0\) and after time \(t\), the number decreases to \(N\). It is found that the graphical representation \(\mathrm{ln} N\) versus \(t\) along the \(y\) and \(x\) axis respectively is a straight line. Then the slope of this line is:
1. \(\lambda\)
2. \(-\lambda\)
3. \(\lambda^{-1}\)
4. \(-\lambda^{-1}\)
Assertion (A): | In a radioactive disintegration, an electron is emitted by the nucleus. |
Reason (R): | Electrons are present inside the nucleus. |
1. | Both (A) and (R) are true and (R) is the correct explanation of (A). |
2. | Both (A) and (R) are true but (R) is not the correct explanation of (A). |
3. | (A) is true but (R) is false. |
4. | (A) is false but (R) is true. |
Assertion (A): | \(\alpha \text-\text{decay}\) atomic number of the daughter nucleus is reduced by \(2\) units from the parent nucleus. | In
Reason (R): | \(\alpha \text-\text{particle}\) carries four units of mass. | An
1. | Both (A) and (R) are True and (R) is the correct explanation of (A). |
2. | Both (A) and (R) are True but (R) is not the correct explanation of (A). |
3. | (A) is True but (R) is False. |
4. | Both (A) and (R) are False. |
Assertion (A): | A beam of charged particles is employed in the treatment of cancer. |
Reason (R): | Charged particles on passing through a material medium lose their energy by causing ionization of the atoms along their path. |
1. | Both (A) and (R) are true and (R) is the correct explanation of (A). |
2. | Both (A) and (R) are true but (R) is not the correct explanation of (A). |
3. | (A) is true but (R) is false. |
4. | Both (A) and (R) are false. |