91Ó°ÊÓ

The amount of matter contained in an atom of an element is called its atomic mass.

\(A = N + Z\)

Where A is atomic mass number

Z= Number of protons in a nucleus

X= symbol for the element

In the expression below:

\(_Z^A{X_N}\)

Z = Number of protons in a nucleus

X= symbol for the element

We know that

\(A = N + Z\)

Where A is atomic mass number

The atomic mass of \(_1^3{{\rm{H}}_2}\) is 3 and

\(\begin{align}A &= 3\\Z &= 1\;\\N &= 2\end{align}\)

An electron and an antineutrino are released as a result of Beta decay.

\(\begin{align}A &= 3\\N &= 1 - ( - 1) = 2\\Z &= A - N\\ & = 3 - 2\\ &= 1\end{align}\)

As charge on beta particle is negative, so \({\beta ^ - }\) Decay equation of \(_1^3{H_2}{\rm{ is }}_1^3{H_2} \to _2^3H{e_1} + {\beta ^ - } + \overline {{\nu _e}} \)

Therefore, \({\beta ^ - }\) Decay equation of \(_1^3{H_2}{\rm{ is }}_1^3{H_2} \to _2^3H{e_1} + {\beta ^ - } + \overline {{\nu _e}} \).