Which of the following figures correctly represents the shape of curve of binding energy per nucleon as a function of mass number?

Assertion (A) : The potential energy of an electon revolving in any stationary orbit in a hydrogen atom is positive.

Reason (R) : The total energy of a charged particle is always positive.

The energy of an electron in the ground state of hydrogen atom is -13.6 eV . The kinetic and potential energy of the electron in the first excited state will be

The potential energy between two nucleon's inside a nucleus is minimum at a distance of about