Name at least one other familiar item that could serve as a model for isotopes

one state would change   like louisiana to texas. thats a change

explanation:

10 years is the answer

for step 7 table c on the lab "newtons law of action"   the average time it took the car to travel .25 meters   was 1.92 seconds.

the average time it took the car to travel 0.50 meters was 2.61 seconds

hope this : )