The total energy of an electron in an atom in an orbit is −3.4 eV. Its kinetic and potential energies are, respectivély :

CONCEPT:

The total energy of an electron is equal to the sum of kinetic energy and potential energy. It is written as;

T.E. = K.E. + P.E.

Here, T.E. is the total energy, K.E. is the kinetic energy and P.E. is the potential energy.

Kinetic energy is defined as the motion of the electron when some energy is applied to the system and potential energy is defined as the energy which is stored in the object by the relative position.

CALCULATION:

Given: The total energy of an electron, T.E. = -3.4 eV.

The kinetic energy K.E. is the negative of the total energy of an electron. It is written as;

K.E. = -T.E.

⇒ K.E. = -(-3.4)

⇒ K.E. = 3.4 eV

and potential energy is twice the total energy. It is written as;

P.E. = 2T.E.

⇒ P.E. = 2(-3.4)

⇒ P.E. = -6.8 eV.

Hence, option 3) is the correct answer.