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

A nucleus X emits a $$\beta $$-particle to produce a nucleus Y. If their atomic masses are M_x and M_y respectively, then the maximum energy of the $$\beta $$-particle emitted is (where, m_e is the mass of an electron and c is the velocity of light)