The correct answer is #4. They have the same number of protons but a different number of neutrons.
Answer:
Explanation:
To plot the given forces of 0.8 N and 0.9 N. It is convenient to take
0.1 N as 1 unit in Graph
For example, 1 unit in the graph is 1 cm
then take 0.1 N equivalent to 1 cm

Yes they can.
Don't really know any examples