8) What is the ratio of the probability of finding an electron at the nucleus to the probability of finding it at Bohr′s radius?

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: