Explain why the statement “the speed of light is 300 million m/s” is not always correct.

Because the speed of light is determined by the medium that is it in. If light is in a vacuum it goes 300 million meters per second but it is slower in air, and even slower in water because water is more dense than the previous two.

a. energy is absorbed in the reaction.

if in a given reaction the energy of products is greater than the energy of reactants it means that reaction is endothermic and during the reaction, the energy is absorbed by reactants. in an endothermic reaction, the products have more stored chemical energy than the reactants. and in this reaction the reactants are more stable than products before the compounds with less energy are always more stable.