Q165 / 180 · COMEDK 2013 · Physics

If $M$ is the atomic mass and $A$ is the mass number, packing fraction is given by

  • A
    $\frac{M}{M-A}$
  • Correct answer
    B
    $\frac{M-A}{A}$
  • C
    $\frac{A}{M-A}$
  • D
    $\frac{A-M}{A}$

Solution

Packing fraction is the ratio of mass defect to the number of nucleons. Mass defect is the difference in the actual isotopic mass $(M)$ and mass number $(A)$. $\therefore$ Packing fraction $=\frac{M-A}{A}$ where, $A$ is mass number or number of nucleons.

Hence, the correct answer is option: 'B'.

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