The correct statement (s) among the following is/are (i) The vibrational energy levels of a real diatomic molecule are equally spaced. (ii) At 500K, the reaction A→B is spontaneous when $\Delta \mathrm{H}=18.83 \mathrm{kJ} \mathrm{mol}^{-1}$ and $\Delta \mathrm{S}=41.84 \mathrm{J} \mathrm{K}^{-1} \mathrm{mol}^{-1}$. (iii) The process of fluorescence involves transition from a singlet electronc state to another singlet electronic state by absoprtion of light. (iv) When a constant P is added to each of the possible energies of a system, its entropy remains unchanged.