The H minus atom starts with a neutral hydrogen atom and adds a single electron into a single bound state at energy -E (you don't need to look up the value of E). Assuming that all the hydrogen is either neutral, or in the H minus state, find how the fraction that is H minus scales with the gas density at fixed T, and for a fixed external radiation field (no internal radiation) under the following types of equilibrium, neglecting stimulated emission, (purely hypothetical for H minus): (a) LTE (i.e., Saha) (b) CIE (ionization is collisional, recombination is radiative) (c) H II regions (all rates are radiative)