How does atmospheric pressure at sea level compare to the atmospheric pressure on the top of a mountain? Explain.

At the top of a mountain the molecules are less dense and there is less air pressure. While at sea level the molecules are more dense and there is more air pressure.

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