Why does the atmosphere weigh so much

i had this on my unit activity, i can you if you are a plato student. are you a plato student?

in theory, limestone is composed principally of the compound calcium carbonate - caco3, but in reality this compound is deposited in conditions involving a number of other compounds as impurities so it ends up being a mixture of many compounds.

hope this : -)

tony (lordcaos066)