Find the number of electrons present in $34 \ g$ of $NH_{3(g)}$. (Express your answer in terms of $N_A$)

In which of the following pairs do $1 \text{ g}$ of each contain the same number of molecules?
$(I)\, N_2O$ and $CO$               $(II)\,N_2$ and $CO_2$
$(III)\, N_2$ and $CO$                $(IV) \,N_2O$ and $CO_2$

Calculate the number of moles present in $9.10 \times 10^{-2} \ kg$ of water.

How many molecules are present in one gram of hydrogen? (Value $\times 10^{23}$)

The number of atoms in $558.5 \ g$ of $Fe$ is equal to: [Atomic mass of $Fe = 55.85 \ g/mol$]

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 $N_A = 6.0 \times 10^{23} \ mol^{-1}$)