Question

Sulphur-$35 (34.96903 \,amu) $emits a $\beta$ particle but no $\gamma$-rays, the product is chlorine-$35 (34.96885\, amu)$. The maximum energy emitted by the $\beta$-particle is:

• A. 0.016767 MeV
• B. 1.6758 MeV
• C. 0.016758 MeV
• D. 16.758 MeV

Answer 1

Answer: (A)

The maximum energy emitted by $\beta$-particles is equal to binding energy.
Binding/energy $=$ mass defect $\times 931.5\, MeV$
Given, mass of sulphur $=34.96903 \,amu$
Mass of chlorine $=34.96885\, amu$
Mass defect $=$ mass of sulphur $-$ mass of chlorine
$=34.96903-34.96885=0.00018\, amu$
$\therefore $ Binding energy $=$ mass defect $\times 931.5\, MeV$
or $=0.00018 \times 931.5 \,MeV $
$=0.16767 \,MeV$