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

What is the number of $CO_2$ molecules in $45.42 \ L$ at $\text{STP}$? (Consider molar volume of gas at $\text{STP} = 22.71 \ L \ mol^{-1}$)

There are $6.02 \times 10^{22}$ molecules each of $N_2$,$O_2$,and $H_2$ which are mixed together at $760 \ mm$ and $273 \ K$. The mass of the mixture in grams is:

$A$ person adds $1.71 \ g$ of sugar $(C_{12}H_{22}O_{11})$ to sweeten their tea. How many carbon atoms are added? (Molar mass of sugar $= 342 \ g/mol$)

If every person on Earth is given $100$ molecules of sugar,how much sugar $(C_{12}H_{22}O_{11})$ is required? (Assume the population of Earth is $3 \times 10^{10}$ and the molar mass of sugar is $342 \ g/mol$)

The total number of gm-molecules of $SO_2Cl_2$ in $13.5 \ g$ of sulphuryl chloride is