9) The velocity of an electron placed in the 3^rd orbit of H atom will be:

10) The increasing order of the values of e⁄m for electron (e), proton (p), neutron (n) and alpha particle (α) will be:

11) The ratio of radii of Bohr′s 3^rd and 4^th orbits in H atom are:

12) Ionisation energy of Na atom is 4.946 x 10² kJ⁄mol. The wavelength of radiation sufficient to ionise Na atom is:

13) If the shortest wavelength of H atom in Lyman series is x, then the longest wavelength in Paschen series of He⁺ is: