An element \(\mathrm{X}\) decays, first by positron emission, and then two \(\alpha\text-\)particles are emitted in successive radioactive decay. If the product nuclei have a mass number \(229\) and atomic number \(89\), the mass number and the atomic number of element \(\mathrm{X}\) are:
1. \(237,~93\)
2. \(237,~94\)
3. \(221,~84\)
4. \(237,~92\)
90% of a radioactive sample is left undecayed after time t has elapsed. What percentage of the initial sample will decay in a total time 2t?
1. 20%
2. 19%
3. 40%
4. 38%
1. | \(\dfrac{(Z - 13)}{\left(A - Z - 23\right)}\) | 2. | \(\dfrac{\left(Z - 18\right)}{\left(A - 36\right)}\) |
3. | \(\dfrac{\left(Z - 13\right)}{\left(A - 36\right)}\) | 4. | \(\dfrac{\left(Z - 13\right)}{\left(A - Z - 13\right)}\) |
1. | \(1.5\times 10^{17}\) | 2. | \(3\times 10^{19}\) |
3. | \(1.5\times 10^{25}\) | 4. | \(3\times 10^{25}\) |
1. | It may emit \(\alpha\text-\)particle. |
2. | It may emit \(\beta^{+}\) particle. |
3. | It may go for \(K\) capture. |
4. | All of the above are possible. |
If the activity of a radioactive sample drops to 1/32 of its initial value after 7.5 Hours, its half-life will be:
1. 3 Hours
2. 4.5 Hours
3. 7.5 Hours
4. 1.5 Hours
Two nuclei have their mass numbers in the ratio of \(1:3.\) The ratio of their nuclear densities would be:
1. \(1:3\)
2. \(3:1\)
3. \((3)^{1/3}:1\)
4. \(1:1\)
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.