Question

The calculated mass of ${}_{20}C{a}^{40}$ is $40.328$u. It releases $306.3$ MeV energy in a nuclear process. Its isotopic mass is.

• A. $39.998$
• B. $40.6570$
• C. $0.3290$
• D. $2.85\times {10}^4$

Answer 1

Answer: (A)

$39.998$

$BE=\Delta m\times 931$MeV
$306.3=\Delta m\times 931$
$\Delta m=0.3290$
$\Delta m=$ calculated mass $-$ isotonic mass
$-$Isotonic mass $=$\Delta m$-$ calculated mass
$=0.3290-40.328$
$=-39.998$
$\therefore$ Isotopic mass $=39.998$