The kinetic energy of an electron revolving in a stable orbit around the nucleus is E. The total energy of the electron in this orbit will be:

-E

The correct answer is Option (2) → -E

In the Boher model of the atom, the total energy $E_{total}$ of an electron revolving in a stable orbit is related to its kinetic energy $E_{Kinetic}$ and potential energy $E_{potential}$.

$E_{total}=E_{Kinetic}+E_{potential}$

and,

$E_{potential}=-2E_{Kinetic}$

$∴E_{total}=E_{Kinetic}-2E_{Kinetic}$

$=-E$