Mass of magnesium required to produce $220 \ mL$ of hydrogen gas at $STP$ on reaction with excess of dil. $HCl$ is (Given: Molar mass of $Mg$ is $24 \ g \ mol^{-1}$)

......... $cm^3$ is the volume of $0.1 \ N \ HCl$ required to react completely with $1.0 \ g$ of pure calcium carbonate $(Ca = 40, C = 12, O = 16)$.

$NaClO_{3}$ is used,even in spacecrafts,to produce $O_{2}.$ The daily consumption of pure $O_{2}$ by a person is $492 \ L$ at $1 \ atm, 300 \ K.$ How much amount of $NaClO_{3},$ in grams,is required to produce $O_{2}$ for the daily consumption of a person at $1 \ atm, 300 \ K?$
$2NaClO_{3(s)} + Fe_{(s)} \rightarrow 3O_{2(g)} + 2NaCl_{(s)} + FeO_{(s)}$
$R = 0.082 \ L \ atm \ mol^{-1} K^{-1}$

Calculate the mass in $kg$ of $4.48 \ dm^3$ of carbon dioxide $(CO_2)$ at $STP$.

$2 \ g$ of aluminium is treated separately with excess of dilute $H_{2}SO_{4}$ and excess of $NaOH$. The ratio of the volumes of hydrogen evolved is

For the combustion reaction of $1 \ mol$ of benzene,if all reactants and products are in the gaseous state,then $\Delta n_{(g)}$ is equal to ......