Answer:
70% solution is more effective
Explanation:
The 70% solution is more effective at inhibiting microbial growth than the 100% solution of the ethyl alcohol.
This is because the pure ethyl alcohol coagulates the protein that is in contact with it.
Also, pure alcohol will tend to evaporate faster than the 70% solution of the ethyl alcohol and it will not be that much effective.
You could have made sure the books were the same weight and your friends could have done it at the same time as you
