What is the weight of $3.01 \times 10^{23}$ molecules of ammonia in grams?

What is the number of moles and total number of atoms respectively present in $5.6 \ cm^{3}$ of ammonia gas at $STP$?

Explain: Avogadro's Law.

The ratio of the number of oxygen atoms $(O)$ in $16.0 \ g$ ozone $(O_3)$,$28.0 \ g$ carbon monoxide $(CO)$,and $16.0 \ g$ oxygen $(O_2)$ is (Atomic mass: $C = 12$,$O = 16$ and Avogadro's constant $N_A = 6.0 \times 10^{23} \ mol^{-1}$)

How many oxygen atoms are present in $4.4 \ g$ of $CO_2$?

How many moles are present in $0.224 \ L$ of an ideal $H_2$ gas at $STP$ (in $mol$)? (Assume molar volume $= 22.4 \ L \ mol^{-1}$)