How many molecules are in 165 g of carbon dioxide?

Here is the order of steps you take to figure out this question:
First you need to know how many moles you would get from 165 g of carbon dioxide. You do that by doing: 
Carbon = 12
Oxygen 2 = 16 x 2 = 32
Total: 32 + 12 = 44  

 -Next you have to use proportions
1 mol CO2 x 1 mol CO2 44 g
= or =
44 g 165 x 165 g

165/44 = 3.75 moles CO2  

 - Last step is to multiply the amount of moles by Avogadro's number, 6.02 x 10^23
3.75 x 6.02 x 10^23 = 2.25 x 10^24 molecules 

Hope this helped

All the elements are arranged by melting points on the periodic table. in row they go from metals to gasses. in the row from sodium to argon, sodium is more reactive than the one on its right, magnesium.