Atoms of a given elements with have the same mass true or false?

If 90.0 grams of ethane reacted with excess chlorine,how many grams of dicarbon hexachloride would form

Which of the following observations indicates that there is a small, dense, positively charged part in the center of an atom? some uncharged particles are scattered by a gold foil. all uncharged particles are attracted towards a gold foil. all positively charged particles pass straight through a gold foil. some positively charged particles bounce back from a gold foil.

Astudent reacts 13 moles of iron with 21 moles of oxygen according to the following equation: