Two chemicals A and B are combined to form a chemical C. The rate, or velocity, of the reaction is proportional to the product of the instantaneous amounts of A and B not converted to chemical C. Initially, there are 40 grams of A and 50 grams of B, and for each gram of B, 2 grams of A is used. It is observed that 20 grams of C is formed in 10 minutes. How much (in grams) is formed in 20 minutes

40 grams.

Explanation:

If 20 grams of C is formed from the combination or reaction of A and B chemicals in 10 minutes, 40 grams of C is formed in 20 minutes because the time is doubled so the concentration of C chemical is also doubled. If the time  is increased further, more concentration of C chemical is produced until the amount of chemicals A and B are present. If we put an enzyme in the solution, the time of the reaction can be reduced.