Atomic weight of boron is 10.81 and it has two isotopes . Then, the ratio of atoms of in nature would be
1. 19 : 81
2. 10 : 11
3. 15 : 16
4. 81 : 19
The half-life of radium is 1600 yr. The fraction of a sample of radium that would remain
after 6400 yr
1.
2.
3.
4.
The count rate of a Geiger Muller counter for the radiation of a radioactive material of half-life 30 min decreases to 5 after 2 h. The initial count rate was
1. 20
2. 25
3. 80
4. 625
1. | \(A\) and \(C\) are isotopes |
2. | \(A\) and \(C\) are isobars |
3. | \(A\) and \(B\) are isotopes |
4. | \(A\) and \(B\) are isobars |
The radius R of a nuclear matter varies with A as
1.
2.
3.
4.
Number of nuclei of a radioactive substance at time t = 0 are 2000 and 1800 at time t = 2s. Number of nuclei left after t = 6s is
1. 1442
2. 1554
3. 1652
4. 1458
In a radioactive material, the activity at time is and at a later time, is . If the decay constant of the material is , then:
1.
2.
3.
4.
Which of the following are suitable for the fusion process ?
1. Light nuclei
2. Heavy nuclei
3. Elements lying in the middle of periodic table
4. Elements lying in the middle of binding energy curve
In the nuclear reaction: \(\mathrm{X}\left(n,\alpha\right){}_{3}^{7}\mathrm{Li}\) the term \({X}\) will be:
1. | \({}_{5}^{10}\mathrm{B}\) | 2. | \({}_{5}^{9}\mathrm{B}\) |
3. | \({}_{5}^{11}\mathrm{B}\) | 4. | \({}_{2}^{4}\mathrm{He}\) |
Two radioactive substances A and B have decay constants and respectively. At t=0 they have the same number of nuclei. The ratio of number of nuclei of A to those of B will be after a time interval
1.
2.
3.
4.