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

The number of moles of electrons in $1 \ kg$ of electrons is .......

$1.4 \, mol$ of phosphorus trichloride $(PCl_{3})$ are present in a sample. How many atoms are there in the sample?

The number of $Cl^{-}$ ions in $333 \ g$ of anhydrous $CaCl_2$ will be ................ $N_A$.

If $10^{20}$ grains are distributed in one second,then the time taken to distribute an Avogadro number of grains is ........ hours.

Natural abundances of $^{12}C$ and $^{13}C$ isotopes of carbon are $99\,\%$ and $1\,\%$,respectively. Assuming they only contribute to the molecular weight of $C_2F_4$,the percentage of $C_2F_4$ having a molecular mass of $101$ is $.....$