Imagine removing one electron from He4 and He3. Their energy levels, as worked out on the basis of Bohr model will be very close. Explain why?

Hint: The energy levels depend on the nuclear mass.
On removing one electron from He4 and He3, the energy levels, as worked out on the basis of Bohr model will be very close as both the nuclei are very heavy as compared to electron mass. Also after removing one electron from He4 and He3 atoms contain one electron and are hydrogen like atoms.