If an electron and a positron annihilate, then the energy released is:
1.
2.
3.
4.
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. |
nucleus after absorbing energy decays into two \(\alpha- \text{particle}\) and an unknown nucleus. The unknown nucleus is:
1. Nitrogen
2. Carbon
3. Boron
4. Oxygen
An atomic nucleus emits several and radiations and finally reduces to . It must have emitted:
1. 4 and 2
2. 6 and 4
3. 8 and 24
4. 4 and 16
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 |
In nuclear reaction , \(\mathrm {B}\) denotes:
1. Electron
2. Positron
3. Proton
4. Neutron
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. |
The rest energy of an electron is:
1. | 510 KeV | 2. | 931 KeV |
3. | 510 MeV | 4. | 931 MeV |
The Binding energy per nucleon of \(^{7}_{3}\mathrm{Li}\) and \(^{4}_{2}\mathrm{He}\) nucleon are \(5.60~\text{MeV}\) and \(7.06~\text{MeV}\), respectively. In the nuclear reaction \(^{7}_{3}\mathrm{Li} + ^{1}_{1}\mathrm{H} \rightarrow ^{4}_{2}\mathrm{He} + ^{4}_{2}\mathrm{He} +Q\), the value of energy \(Q\) released is:
1. \(19.6~\text{MeV}\)
2. \(-2.4~\text{MeV}\)
3. \(8.4~\text{MeV}\)
4. \(17.3~\text{MeV}\)
A nucleus \({ }_{{n}}^{{m}} {X}\) emits one \(\alpha\text -\text{particle}\) and two \(\beta\text- \text{particle}\) The resulting nucleus is:
1. \(^{m-}{}_n^6 Z \)
2. \(^{m-}{}_{n}^{4} X \)
3. \(^{m-4}_{n-2}Y\)
4. \(^{m-6}_{n-4} Z \)