What is the volume of oxygen required for complete combustion of $0.25 \ mole$ of methane at $\text{S.T.P.}$ (in $dm^3$)?

$23 \ g$ of sodium metal is reacted with water. Find the volume of $H_2$ gas evolved at $STP$ in $mL$.

As per the following equation, $0.217 \ g$ of $HgO$ (molecular mass $= 217 \ g \ mol^{-1}$) reacts with excess iodide. On titration of the resulting solution, how many $mL$ of $0.01 \ M$ $HCl$ is required to reach the equivalence point (in $mL$)?
$HgO + 4 I^{-} + H_2O \longrightarrow HgI_4^{2-} + 2 OH^{-}$

The complete combustion of one mole of benzene produces how many grams of carbon dioxide?

In $Fe_{0.96}O$,$Fe$ is present in $+2$ and $+3$ oxidation states. What is the mole fraction of $Fe^{2+}$ ions in the compound?

The volume of $0.1 \ M$ oxalic acid that can be completely oxidized by $20 \ mL$ of $0.025 \ M$ $KMnO_4$ solution is (in $mL$)