The fuel tank of an airplane has a device that measures the fuel's temperature. Before the airplane
took off, the temperature of the fuel was 27°C. After the airplane had been flying for one hour, the
temperature of the fuel had decreased to 3°C. Which of the following must have happened to the
molecules of the fuel?

sodium (na), for example, has one electron in its valence shell. this is an unstable state because that valence shell needs eight electrons to be full. in order to fill its valence shell, find a way to add seven electrons to its valence shell

adding or remove a gaseous reactant or product changes the concentrations. if the concentration of reactant or product is increased, the system will shift away from the side in which concentration was increased (i.e. if the concentration of reactants is increased, the system will shift toward the products. if more products are added, the system will shift to form more reactants). conversely, if the concentration of reactant or product is decreased, the system will shift toward the side in which concentration was decreased (i.e. if reactants are removed, the system will shift to form more reactants. if the concentration of products is decreased, the equilibrium will shift toward the products).

explanation:

tracks, burrows, eggshells, nests, tooth marks, or gastroliths

it's c (engineer's do their work with mechanical stuff not on any living being)