Answer:
Z=22.70
Explanation:
It is given that,
An element Z that has two naturally occurring isotopes with the following percent abundances as follows :
The isotope with a mass number 22 is 65.0% abundant; the isotope with a mass number 24 is 35.0% abundant.
The average atomic mass for element Z is given by :

So, the average atomic mass for element Z is 22.70.
An example is when on a seesaw if a kid is on one side and an adult is on the other then it is unbalanced because the adult weighs more
I believe the answer is 1-Water :)
A control group is the group in an experiment that does not receive any sort of change, to then be compared to the other treated objects at the end of the study.