What is a roman numeral most likely needed in the name of an ionic compound ?

Label a-f based on the table using c for concentrated and d for dilute

Reduction is a reaction which results in a in electrons and a in positive charge of the atom or ion 1) a- loss 1) b- gain 2) a-increase 2) b-decrease

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?