Third Bohe orbit is a reference to the fundamental quantum number 3.
Now, the energy of an electron for n = n is En = – 13.6/n2 eV for hydrogen Atom.
In Bohr’s theory, we can see the equation:En= (1/2) ( potential energy).
Thus, (1/2)(potential energy )=-(13.6/9)eV.
Therefore, potential energy =-27.2/9 eV……………..(1)
Now the kinetic energy K is the total energy potential energy
Then, K=-13.6/9-(-27.2/9)=13.6/9 eV.