Question

How does positron emission occur?

Answer 1

Hint The radioactive substances have unstable nuclei. As a result, the radioactive substances disintegrate and this leads to the formation of a stable nuclei and there is also release of some energy.

Complete answer:
When the radioactive substance disintegrates to form a stable nucleus, there are three types of decays which take place, the alpha decay gives alpha particles and the beta decay forms a beta particle and the gamma decays forms a gamma particle. The material which has unstable nuclei is known as radioactive substance.
Positron is the type of $\beta$ -particle. Most of the nucleus are unstable due to the greater number of protons present in the nucleus or due to the ratio of neutrons and protons in the nucleus is not 1:1.
The proton emission leads to the increase in the number of neutrons and decrease in the number of protons which makes the nucleus more stable and balanced. The positron is ${\beta }^{+}$ .

Additional information:
Let’s understand the three decays in detail:
The first decay is alpha decay. During this decay there is release of alpha particles from the nucleus. The alpha particles are the helium nucleus. The second type of decay is known as beta decay. During this decay there is release of positrons from the nucleus. The third type of decay is known as gamma decay. During this decay there is emission of gamma particles from the nucleus.

Note: The alpha particle contains two protons and two neutrons because the alpha particle is the helium nucleus. The two electrons are donated which gives the alpha particle a +2 charge. Protons are different from the alpha particles; they contain only one proton.