Question

How many number of moles of 2.8 litres of any gas at S.T.P. make?

Answer 1

The standard relation connecting the above two terms is :
$22.4$ litres of any gas at $S.T.P.$ $\stackrel{make}{\to }1mole$.
$2.8litres\stackrel{make}{\to }xmoles$.
$x=\frac{2.8\times 1}{22.4}=\frac{1}{8}=0.125$
Therefore, $2.8$ litres of any gas at $S.T.P.$ make $0.125$ moles.