Suppose in a hypothetical world the angular momentum is quantized to be even integral multiples of $${h \over {2\pi }}$$. The largest possible wavelength emitted by hydrogen atoms in visible range in a world according to Bohr's model will be,

(Consider hc = 1242 Mev-fm)

A 12.5 eV electron beam is used to bombard gaseous hydrogen at ground state. The energy level upto which the hydrogen atoms would be excited is

Let r, v, E be the radius of orbit, speed of electron and total energy of electron respectively in H-atom. Which of the following quantities according to Bohr theory, is proportional to the quantum number n ?

If R is the Rydberg constant in cm^-1, then hydrogen atom does not emit any radiation of wavelength in the range of