JEE Advanced Model Paper 11 with solutions for online practice

A photon beam containing various energies is passed through a sampleof H - atoms in ground state. Another photon beam containing various energies ispassed through a sample of Li2+ ions in ground state. The two photon beams arenon – identical .Assume that excitation of electrons takes place in a single step to different energy levels, but de – excitation takes place in several possible steps toground state. Let x1 and z2 be the number of dark lines in the absorption spectra ofH - atoms and Li2+ ions respectively and y1 and y2 be the number of bright lines inthe emission spectra of H - atoms and Li2+ ions respectively. If x1+x2 = 15 , then the minimum value of y1+y2 = 14N + 8. What isN?