Ihave a question on my chem homework. it's asking "how many molecules of n2o4 are in 76.3 g n2o4? the molar mass of n2o4 is 92.02 g/mol." i am really confused as to how to do this. ? ?

Here, Molar mass of N2O4 = 92.02 g/mol
So, Number of molecules in 1 mole (92.02 g) = 6.023 * 10²³
Number of molecules in 76.3 g = 6.023 * 10²³ / 92.02  * 76.3
= 6.023 * 10²³ / 1.20
= 5 * 10²³ 

In short, Your Answer would be approx. 5 * 10²³ molecules

Hope this helps!

They are like other investigations? say there was a murder u have to do blood test and finger prints which run through a lab. 

Replicate prove reliability and validity