What is meant by the following?
$(i)$ Molar mass
$(ii)$ Valency

Calculate the number of atoms in $60$ grams of carbon.

Calculate the number of atoms in $120 \, g$ of calcium and $120 \, g$ of iron. Which one has more number of atoms and what is the difference? (Given: atomic mass of calcium $= 40 \, u$ and iron $= 56 \, u$)

Fill in the missing data in the Table.

Species property	$H_2O$	$CO_2$	$Na$ atom	$MgCl_2$
No. of moles	$2$	-	-	$0.5$
No. of particles	-	$3.011 \times 10^{23}$	-	-
Mass	$36 \, g$	-	$115 \, g$	-

Compute the number of ions present in $5.85 \, g$ of sodium chloride.

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 $1\, g\, cm^{-3}$.