Question

The correct relation between the packing fraction $P$ and mass number $A$ is

• A. $P$ = $\frac{M-A}{A}$
• B. $P$ = $\frac{M+A}{A}$
• C. $P$ = $\frac{A}{M-A}$
• D. $P$ = $\frac{A}{M+A}$

Answer 1

The correct option is A $P$ = $\frac{M-A}{A}$

Packing fraction $P=\frac{Isotopemass-massnumber}{massnumber}$

This fraction can have positive or can have negative sign. A positive packing fraction describes a tendency towards instability. A negative packing fraction means isotopic mass is less than actual mass number. This difference is due to the transformation of mass into energy in the formation of nucleus. A plot of packing fraction against corresponding mass no’s of various elements is as shown.