Question

Tritium is an isotope of hydrogen whose nucleus triton contains $2$ neutrons and $1$ proton. Free neutrons decay into $p + \vec{e} + \vec{v}$ . If one of the neutrons in triton decays, it would transform into $_{2}He^3$ nucleus. This does not happen. This is because

• A. Triton energy is less than that of a $He^3$ nucleus
• B. the electron created in the beta decay process cannot remain in the nucleus
• C. both the neutrons in triton have a decay simultaneously resulting in a nucleus with $3$ protons, which is not a $He^3$ nucleus
• D. because free neutrons decay due to external perturbations which is absent in a triton nucleus

Answer 1

Answer: (A)

Triton $\left({ }_{1} H ^{3}\right)$ has $1$ proton and $2$ neutrons. If a neutron decays as $\rightarrow p +\vec{ e }+\vec{ v }$, then nucleus will have $2$ proton and $1$ neutron, ie. triton atom converts in ${ }_{2} He ^{3}$ ($2$ proton and $1$ neutron)
Binding energy of $\left({ }_{1} H ^{3}\right)$ is much smaller than ${ }_{2} He ^{3}$ so transformation is not possible energetically