Verify by calculating that:
$(a)$ $5 \, mol$ of $CO_2$ and $5 \, mol$ of $H_2O$ do not have the same mass.
$(b)$ $240 \, g$ of calcium and $240 \, g$ of magnesium elements have a mole ratio of $3:5$.

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 number of molecules in $90$ grams of water.

Which of the following would weigh the highest?

$3.42 \, g$ of sucrose $(C_{12}H_{22}O_{11})$ is dissolved in $18 \, g$ of water $(H_2O)$. The number of oxygen atoms in the solution is:

Calculate the formula unit masses of $ZnO, Na_2O, K_2CO_3$ given atomic masses of $Zn=65\,u, Na=23\,u, K=39\,u, C=12\,u$ and $O=16\,u$.