How many carbon atoms are contained in 2.8g of C2H4?

Answer 1

There are 2.8/molar mass C2H4 moles in 2.8 g C2H4.
There are 6.022 x 10^23 molecules in a mole of molecules. And you have ?? moles.

Answer 2

explian how you got 6.002 x 10^23

Answer 3

6.022 x 10^23 is Avogadro's number, you use this to find the amount of particles in the concentration (moles)