Answer :
Answer: Option (1) is the correct answer.
Explanation:
- A positron is a small particle which contains a +1 charge and its mass is equal to the mass of an electron, that is, [tex]9.109 \times 10^{-31}[/tex] kg.
A positron is represent by the symbol [tex]^{0}_{+1}\beta[/tex].
For example, [tex]^{37}_{19}K \rightarrow ^{37}_{18}Ar + ^{0}_{+1}\beta[/tex]
- Whereas nitrogen-16 does not decay to give a positron because nitrogen-16 is the daughter isotope formed due to decay of oxygen-16.
The decay reaction is as follows.
[tex]^{16}_{8}O \rightarrow ^{16}_{7}N + ^{0}_{+1}\beta[/tex]
- And, on radioactive decay of thorium-232 there will be formation of radium-228 along with emission of an alpha particle.
The reaction will be as follows.
[tex]^{232}_{90}Th \rightarrow ^{228}_{88}Ra + ^{4}_{2}\alpha[/tex]
Therefore, we can conclude that out of the given options positrons are spontaneously emitted from the nuclei of potassium-37.