The number of moles of sodium oxide in $620 \ g$ of it is ................ $moles$.

Arrange the following in order of increasing mass:
$I$. $1$ mole of $N_2$
$II$. $0.5$ mole of $O_3$
$III$. $3.011 \times 10^{23}$ molecules of $O_2$
$IV$. $0.5$ gram atom of $O$

$5.6 \, L$ of oxygen at $STP$ contains .............

What is the number of molecules in $4.25 \ g$ of $NH_3$?

$A$ sample of $[Cu(NH_3)_4]SO_4$ contains $2.4 \times 10^{24}$ ammonia molecules. The moles of $[Cu(NH_3)_4]SO_4$ in the given sample will be:

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