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 ${}_{2}H{e}^3$ nucleus. This does not happen. This is because

• A. Triton energy is less than that of a $H{e}^3$ 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 $H{e}^3$ 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 $\to p+\vec{e}+\vec{v}$, then nucleus will have $2$ proton and $1$ neutron, ie. triton atom converts in ${}_{2}H{e}^3$ ($2$ proton and $1$ neutron)
Binding energy of $\left({}_1{H}^3\right)$ is much smaller than ${}_{2}H{e}^3$ so transformation is not possible energetically