Which of the following is NOT an equilibrium reaction? choose all that apply a. CH4 + O2 --> CO2 + H2O
b. HCl + H2O --> H3O+ + Cl-
c. H2O (s) --> H2O (l)
d. FeCl2 (aq) + CeCl4 (aq) --> FeCl3 (aq) + CeCl3 (aq)

Also, which reaction from above will have the lowest K?

please explain how you answered the questions.

Thank you!

Consider hydrogen in an excited state n = 5n=5 that emits photons to reach the ground state. there are various possible transitions other than straight to the ground state that can occur; for example, it can drop to the n = 3n=3 state followed by the n = 3n=3 to the ground state transition. which of the possible transitions will result in the emission of a photon in the visible region?