Tamil Nadu Board Solutions for Chapter: Atoms and Molecules, Exercise 4: Activity 7.3

Under same conditions of temperature and pressure if you collect $3$ litre of ${\mathrm{O}}_2$, $5$ litre of ${\mathrm{Cl}}_2$ and $6$ litre of ${\mathrm{H}}_2$, 

Which has the highest number of molecules?

Under same conditions of temperature and pressure if you collect $3$ litre of ${\mathrm{O}}_2$, $5$ litre of ${\mathrm{Cl}}_2$ and $6$ litre of ${\mathrm{H}}_2$, Which has the lowest number of molecules?