The substance which is a combination of different atoms is a compound.
I Would think it would be C Since Humans can't live 500 years but then yet again it is light years not regular years i think if you find how man years is 500 light years the that could help you in finding the answer
This law<span> states that the pressure of a given amount of </span>gas<span> held at constant volume is directly proportional to the Kelvin temperature. Therefore, the variables are pressure and temperature. Hope this answers the question. Have a nice day.</span>
Molarity = moles/litre
mol/L=g/(g/mol) (which is g times mols per g)
will give you mols then divide that by L to get mol/L
so
M=g x mol/g x L
M=(20 x 1 x 1.50)/39.997