Atoms

Answer (d) inversely proportional to

The positively charged nucleus, has electrons revolving around it in stationary orbits. The Coulomb's force provides the necessary centripetal force of attraction to keep the electrons is orbits.

The wavelength of lines is given by For Lyman series, the shortest wavelength is for and longest is for (i) (ii) Dividing E (ii) by E (i), we get Given,

When the electron loses whole of its energy in a single collision with the atoms, an -ray photon of maximum energy is emitted ie, Minimum wavelength = cut-off wavelength of -ray

According to Bohr's model

Mass number of an atom is the sum of nucleons, i.e., the sum of number of protons and that of neutrons.