Fission of nuclei is possible because the binding energy per nucleon in them:
1. | increases with mass number at high mass numbers. |
2. | decreases with mass number at high mass numbers. |
3. | increases with mass number at low mass numbers. |
4. | decreases with mass number at low mass numbers. |
During negative -decay:
1. | a neutron converts into proton. |
2. | a proton converts into neutron. |
3. | neutron to proton ratio increases. |
4. | None of these |
From a newly formed radioactive substance (Half-life 2 hours), the intensity of radiation is 64 times the permissible safe level. The minimum time after which work can be done safely from this source is:
1. 6 hours
2. 12 hours
3. 24 hours
4. 128 hours
The half-life of a radioactive substance is 20 minutes. The time between 20% and 80% decay will be:
1. 20 minutes
2. 40 minutes
3. 30 minutes
4. 25 minutes
The mass of an -particle is:
1. | less than the sum of masses of two protons and two neutrons. |
2. | equal to the mass of four protons. |
3. | equal to the mass of four neutrons. |
4. | equal to the sum of masses of two protons and two neutrons. |
1. | \(510\) KeV | 2. | \(931\) KeV |
3. | \(510\) MeV | 4. | \(931\) MeV |