The concept used here is the Le Chatelier's principle. When a disturbance is introduced to the system, it favors the direction of reaction that minimizes the disturbance to regain equilibrium.
In endothermic reactions, the forward reaction is favored when the temperature is low. Otherwise, the reverse reaction is favored. When you add the amounts of substances on the reactant side, more products would formed favoring the forward reaction. If you increase concentration on the product side, you form more reactants so it would favor the reverse reaction. Lastly, since 10 moles of gases are needed in the reactant side, it would be favored during high pressure reaction.
This is categorized as a combustion reaction.
You should clean up after every investigation because if you leave a mess, maybe another detective will come in and get lost because of the mess you left.
D) burning magnesium ribbon, as combustion is a chemical reaction so causes chemical change. The other 3 options do not involve reactions so there isn't a chemical change.
