Question

What is the mass in grams of 6.12 x 10^20 molecules of caffeine, C8H10N4O2?

Answer 1

$6,02*10^{23} \ \ \ \ \ \ \rightarrow \ \ \ \ \ 194,2g\\ 6,12 * 10^{20} \ \ \ \ \ \ \rightarrow \ \ \ \ \ x\\\\ x=\frac{6,12*10^{20}*194,2g}{6,02*10^{23}}\approx197*10^{-3}g=0,197g$