Class 12 NEET Physics Atoms and Nuclei Questions Part 2

Energy of an hydrogen like atom like He+ in an nth orbit is given by
En=−

13.6Z2

n2

eV
For hydrogen atom, Z=1
∴En=−

13.6

n2

eV
For ground state, n=1
∴E1=−

13.6

12

eV=−13.6eV
For He+ ion, Z=2
En=−

4(23.6)

n2

eV
For first excited state,n=2
∴E2=−

4(13.6)

(2)2

eV=−13.6eV
Hence, the energy in He+
ion in first excited state is same that of energy of the hydrogen atom in ground state i.e.−13.6eV