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?

For a gaseous reaction $Cl_{2(g)} + PCl_{3(g)} \to PCl_{5(g)}$. If $10 \ mL$ of $Cl_2$ completely react with $PCl_3$,then find out the produced volume of $PCl_5$ in $mL$.

Given the reaction $C_{(s)} + H_2O_{(l)} \to CO_{(g)} + H_{2(g)}$,calculate the volume of the gases produced at $STP$ from $48.0 \ g$ of carbon.

Ferrous sulphate heptahydrate is used to fortify foods with iron. The amount (in $grams$) of the salt required to achieve $10 \; ppm$ of iron in $100 \; kg$ of wheat is
Atomic weight : $Fe = 55.85$,$S = 32.0$,$O = 16.00$

What will be the amount of $MgCl_2$ (in $g$) when $17 \ g$ of $HCl$ is reacted with an excess of $MgO$ in the following reaction: $MgO + 2HCl \to MgCl_2 + H_2O$?

$A$ pre-weighed vessel is filled with $O_2$ and weighed at $STP$. It is then evacuated and filled with $SO_2$ gas at the same temperature and pressure,and weighed again. The weight of $O_2$ will be: