They can use them to find the age of fossils.
Increasing the concentration of one or more reactants will often increase the rate of reaction. This occurs because a higher concentration of a reactant will lead to more collisions of that reactant in a specific time period.
Reaction rate increases with concentration, as described by the rate law and explained by collision theory. As reactant concentration increases, the frequency of collision increases. The rate of gaseous reactions increases with pressure, which is, in fact, equivalent to an increase in concentration of the gas.
Complex compounds are broken down to simpler substances in catabolic reactions.
These kinds of reactions often occur in biological systems. In living organisms, complex compounds like lipids, proteins and complex sugar like cellulose are broken down into simpler forms. Products of these reactions are simple sugars, amino acids etc. but a certain amount of energy is also produced and stored in energy molecules for future use.
The correct answer would be D: Physical properties can be observed without changing the identity of a substance
