How many grams are there in the following? 

$2$ moles of hydrogen molecule, ${\mathrm{H}}_2$.

How many grams are there in the following? 

$3$ moles of chlorine molecule, ${\mathrm{Cl}}_2$.

How many grams are there in the following? 

$5$ moles of sulphur molecule, ${\mathrm{S}}_8$.

How many grams are there in the following? 

$4$ moles of phosphorous molecule, ${\mathrm{P}}_4$.

Calculate the $\%$ of each element in calcium carbonate. (Atomic mass: $\mathrm{C}-12\mathrm{u}, \mathrm{O}-16\mathrm{u}, \mathrm{Ca} -40\mathrm{u}$). 

Calculate the $\%$ of oxygen in ${\mathrm{Al}}_2({\mathrm{SO}}_4{)}_3$.(Atomic mass: $\mathrm{Al}-27\mathrm{u}, \mathrm{O}-16\mathrm{u}, \mathrm{S} -32\mathrm{u}$).