1. A simple equation for the reaction: 2 KNO3 (aq) + C (s) + S (s) -> K2S (s) + N2 (g) + 3 CO2 (g) The oxidation number of carbon increases from 0 to +4. The oxidation number of nitrogen decreases from +5 to 0. The oxidation number of sulphur decreases from 0 to -2. Are these correct? 2. "Sulfur is used to speed up the reaction and acts like a catalyst in that it increases the rate of reaction. However, unlike a catalyst, it is used up in the reaction." I understand that transition metals are often used as catalysts but why can sulphur act like a catalyst? 3. Potassium Nitrate is a naturally occurring compound. Can we find them easily? Do we often produce it by neutralizing nitric acid with potassium hydroxide? 4. When metals are burnt, coloured metal oxides are formed. Is this the only reason for the beautiful colours of fireworks? When metals are burnt under high temperature, will they turn to plasma state? If so, should the metal ions be responsible for the colours and sparks?