Examining a chemical system before and after a reaction reveals the a. net chemical change. b. reaction mechanism. c. intermediates. d. activated complex

Option (a) is the correct answer.

Explanation:

A chemical change is defined as the change which brings difference in the composition of reacting species.

Therefore, during a chemical change there will always be formation of new compounds.

For example, is a chemical change as new substance formed is NaCl.

So basically, a chemical reaction equation or system tells the overall change occuring in the system.

Mechanism of a reaction can only be determined theoretically and not just by examining a chemical system.

Intermediates cannot be isolated as they are very reactive species. Hence, they cannot be determined by examining a chemical system.

Activated complex are the intermediate substances which are formed during the reaction and they cannot be isolated. Hence, they cannot be determined by examining a chemical system.

Thus, we can conclude that examining a chemical system before and after a reaction reveals the net chemical change.

c (diamond),

sio2 (quartz)