Question

The Q-value for the $\alpha -decay$ of ${}_{88}^{226}Ra$ is (approximately)

• A. 4.93 MeV
• B. 2.46 MeV
• C. 9.8 MeV
• D. 14.7 MeV

Answer 1

Answer: (A)

4.93 MeV

$\begin{array}{c}{}_{88}^{226}Ra⟶{}_2^{4}H{e}^{2+}+{}_{86}^{222}Rn\end{array}$

$226.02540\mu 4.00260\mu 222.01750\mu$

$\begin{array}{cc}\Delta m=& 0.0053\\ Q\text{-value}& =\Delta m\times 931.5MeV\\ & =0.0053\times 931.5\\ & =4.93695\end{array}$