The hydrated salt $Na_2SO_4 \cdot nH_2O$ undergoes $55.9 \%$ loss in weight on heating and becomes anhydrous. The value of $n$ will be?

$A$ sample of $NaNO_3$ weighing $0.38 \ g$ is placed in a $50.0 \ mL$ volumetric flask. The flask is filled to the mark with water. What is the molarity of the solution?

If $500 \ mL$ of $CaCl_2$ solution contains $3.01 \times 10^{22}$ chloride ions,the molarity of the solution will be: (in $M$)

Some $CO_2$ gas was kept in a sealed container at a pressure of $1 \ atm$ and at $273 \ K$. This entire amount of $CO_2$ gas was later passed through an aqueous solution of $Ca(OH)_2$. The excess unreacted $Ca(OH)_2$ was later neutralized with $0.1 \ M$ of $40 \ mL$ $HCl$. If the volume of the sealed container of $CO_2$ was $x$,then $x$ is $............. \ cm^3$ $(nearest \ integer)$.
$[$Given : The entire amount of $CO_{2(g)}$ reacted with exactly half the initial amount of $Ca(OH)_2$ present in the aqueous solution.$]$

Define stoichiometry and stoichiometric calculation.

Six volumes of oxygen,on complete ozonisation,form ...... volumes of ozone.