Calculate the mass in $kg$ of $2.5 \ mol$ of ammonia.

The largest number of molecules is in

Calculate the number of molecules present in $2.24 \text{ dm}^3$ of carbon dioxide $(CO_2)$ at $STP$.

The number of molecules and atoms present in $1.2 \ g$ of ozone $(O_3)$ are respectively:

In $3$ moles of ethane $(C_{2}H_{6})$,calculate the following:
$i.$ Number of moles of carbon atoms.
$ii.$ Number of moles of hydrogen atoms.
$iii.$ Number of molecules of ethane.

The highest number of helium atoms is in