How many molecules are present in $22400 \ cm^3$ of a gas at $STP$?

Calculate the number of valence electrons in $4.2 \ g$ of $N_3^-$ ions in terms of $N_A$ ($N_A$ = Avogadro constant). (in $N_A$)

The molar mass of $CO_2$ is $44 \ g/mol$. Given that the Avogadro constant is $6.022 \times 10^{23} \ mol^{-1}$,the mass of one molecule of $CO_2$ is ..... $\times 10^{-23} \ g$.

Find out the total number of electrons present in $1.6 \ g$ of methane $(CH_4)$?

What is the number of molecules in $2.125 \text{ g}$ of ammonia $(NH_3)$?

The number of hydrogen atoms in $0.9 \ g$ glucose $(C_6H_{12}O_6)$ $(M_w = 180 \ g/mol)$ is same as