The system that acts as a barrier from the outside the environment is called

because u need two or more forms of the same element that contain equal numbers of protons but different numbers of neutrons in their nuclei to form isotopes.

so since they all have the same shape? i mean maybe because m& m and reeses are both chocolates

im pretty sure its b

b) nuclear ive learned that in a pedtrodic table

the objects have the same charge.