Which is not unique to each element?
a. proton number
b. atomic number
c. neutron number
d. chemical symbol

your answer is D

This is because each element has its own atomic number and it doesnt repeat. Same with the protons and neutrons, thats what makes it special.

But the symbol has nothing to do with the element and can be used to represent any other element.

Hope this helps you out!!

:)))

that tool is called an altimeter which measures your altitude which can be used to tell which atmosphere you are currently in, including the stratosphere.

hope this ! : )

reserve is the answer