$A$ sample of ethane $(C_2H_6)$ gas has the same mass as $1.5 \times 10^{20}$ molecules of methane $(CH_4)$. How many $C_2H_6$ molecules does the sample of gas contain?

In photosynthesis,$6$ molecules of carbon dioxide combine with an equal number of water molecules through a complex series of reactions to give a molecule of glucose having a molecular formula $C_6H_{12}O_6$. How many grams of water would be required to produce $18\, g$ of glucose? Compute the volume of water (in $cm^3$) so consumed assuming the density of water to be $1\, g\, cm^{-3}$.

Calculate the molecular masses of $H_2$,$O_2$ and $Cl_2$.

Which of the following contains the maximum number of molecules?

Do $5$ moles of $CO_{2}$ and $5$ moles of $H_{2}O$ have the same mass?

Calculate the number of molecules of sulphur $(S_8)$ present in $16 \, g$ of solid sulphur.