Question

${}_{13}{\text{Al}}^{27}+{}_2{\text{He}}^4\to {}_{14}{\text{Si}}^{30}+{}_1{\text{H}}^1+\text{Q}$
Mass of ${}_{13}{\text{Al}}^{27}=26.9815\text{amu}$ and mass of ${}_{14}{\text{Si}}^{30}=29.9738$ amu.

The value of Q is equal to :

• A. $4.437\text{MeV}$
• B. $6.578\text{MeV}$
• C. $8.328\text{MeV}$
• D. $2.329\text{MeV}$

Answer 1

The correct option is D $2.329\text{MeV}$

Mass of ${}_2{\text{He}}^4=4.0026;{}^1{\text{H}}_1=1.00783$.
$\text{(amu=931 Mev)}$
Mass defect = $(26.9815+4.0026)-(29.9738+1.0078)$
= $30.9841-30.9816=0.0025\text{amu}$
Hence, Q = $0.0025\times 931=2.329\text{MeV}$.