Question

Element ${}_{26}^{108}\text{Y}$ is formed as a result of 3 $\alpha$ and $2{\beta }^{-}$ decays. Which of the following is the parent element?

• A. ${}_{22}^{96}\Psi$
• B. ${}_{30}^{120}\Lambda$
• C. ${}_{24}^{120}\Omega$
• D. ${}_{14}^{18}\Delta {+}_{18}^{96}{\rm Y}$

Answer 1

Answer: (B)

${}_{30}^{120}\Lambda$

$\alpha ⟶$ mass is 4, $N_{e^{-}}$ is 2 so $3d⟶$ mass$=12,N_{e^{-}}=6$
${\beta }^{-}⟶$ mass is 0, $N_{e^{-}}$ is $-1$ so $2{\beta }^{-}⟶$ mass$=0,N_{e^{-}}=-2$
So, $\Delta$ Mass$=12atm,\Delta N_{e^{-}}=4,$ so parent is ${}_{30}^{120}\Lambda$
which is option $\left(B\right).$