JEE Advanced 2016 Paper 2

The electrostatic energy of Z protons uniformly distributed through out a spherical nucleus of radius R is given by E=

3

5

Z(Z−1)e2

4πε0R

The measured masses of neutron 11H,715N and 815O are 1.008665 u,1.007825u,15.000109 u and 15.003065 u respectively .Given that the radii of both the 715N and 815O nuclei are ame,1u=931.5 MeV/c2 (c is the speed of light) and

e2

(4πε0)

=1.44MeV fm. Assuming that the difference between the binding energies of 715N and 815O is purely due to the electrostatic energy ,the radius of eithr of the nuclei is (1fm=10−15m)