Assertion: Binding energy per nucleon is nearly constant for element in the range A=30 to A=170 .
Reason : The nuclear force between two nucleons falls rapidly to zero as their distance is more than a few femtometres.

Options

A. If both assertion and reason are true and reason is the correct explanation of assertion .
B. If both assertion and reason are true but reason is not the correct explanation of assertion .
C. If assertion is true but reason is false .
D. If both assertion and reason are false

Answer

A

Explanation

The nuclear force between two nucleons falls rapidly to zero as their distance is more than a few femtometers. This leads to saturation of forces in a medium or a large-sized nucleus, which is the reason for the constancy of the binding energy per nucleon.