Question

What is the mass of 10 molecules of nitrogen dioxide, no2, in g? use 3 sig. fig?

Answer 1

Find the molecules in moles. 

10/(6.02 x 10^23) = 1.66 x 10^-23 moles 

mass = moles x molar mass 

m= 1.66 x 10^-23 moles x 46 g mol^-1

m= 7.64 x 10^-22 grams 

Hope I helped :)