Which one is the best description of a chemical reaction?

a. mixing two substances

b. the combustion of a substance

c. forming or breaking bonds

d. the decomposition of particles

The correct answer for this question is C - the best description of a chemical reaction from the answers offered here is that it consists of the forming and breaking of bonds between particles. There are not any atoms destroyed in a chemical reaction, so B and C are incorrect, and although mixing two substances together (as specified in A) could produce a chemical reaction, this is not the best way of describing the actual chemical process.