State whether the following statement is true or false:
Mass of two moles of atoms or molecules is called molar mass.

What is the mass of:
$(a)$ $1$ mole of nitrogen atoms?
$(b)$ $4$ moles of aluminium atoms (Atomic mass of aluminium $= 27$)?
$(c)$ $10$ moles of sodium sulphite $(Na_2SO_3)$?

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 mass of the following compounds:
$(i)$ $NH_{4}NO_{3}$
$(ii)$ $H_{2}SO_{4}$
$(iii)$ $Na_{2}CO_{3}$
$(iv)$ $NaOH$
$(v)$ $HNO_{3}$
$(vi)$ $Al_{2}(SO_{4})_{3}$

Calculate the mass of $20$ water molecules.

Cinnabar $(HgS)$ is a prominent ore of mercury. How many grams of mercury are present in $225 \,g$ of pure $HgS$ (in $,g$)? Molar mass of $Hg$ and $S$ are $200.6 \,g \,mol^{-1}$ and $32 \,g \,mol^{-1}$ respectively.