Imagine an atom made up of proton and a
hypothetical particle of double the mass of the
electron but having the same charge as the
electron. Apply the Bohr atom model and consider
all possible transitions of this hypothetical particle
of the first excited level. The longest wavelength
photon that will be emitted has wavelength λ (in
terms of the Rydberg constant R for hydrogen
atom) equal to :
(A) 9/5R (B) 36/5R (C) 18/5R (D) 4/R