3.00mL of CH4 is known to contain 0.650 moles at a ertain temp and pressure. If the volume of a chamber of CH4 increased from 7.00 L to 8.20 L, how many moles of CH4 were added?

What’s the percent by mass of carbon in c10h14n2

Ican determine the molar mass of an element by looking on the under the atomic mass for the element. for example the molar mass of phosphorus is 30.974 grams/mole. avogadro’s number tells me the amount of representative particles in 1 mole of any substance. this means 12.011 gram sample of carbon and a 32.0 gram sample of sulfur have the same number of atoms.

Chemistry worksheet - i am not sure what they are asking for exactly?