i don't understand any of this !

I'm doing the STP & stuff like that .
The question is;
How Many Molecules are contained in each of the following ?
a] 1.00 mol O2
b] 2.50 mol He
c] 0.0650 mol NH3
d] 11.5g NO2

pls just explain how to do .
i don't need you to just give me an answer , i need explanation. I would actually like you to not provide an answer & i'll check back with you

1 answer

You need one piece of information to answer a,b,and c. A second piece to answer d.

Piece 1. There are 6.022E23 molecules in a mole.Therefore,
a. 1 x 6.022E23 = ??
b. 2.50 x 6.022E23 = ??
c. etc.
d. piece 2 information. moles = grams/molar mass.
Convert 11.5 g NO2 to moles with piece 1, then to molecules with piece 2.