What volume of $0.8 \ M$ solution contains $0.1 \ mole$ of the solute? (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 $mL$)?
$HgO + 4 I^{-} + H_2O \longrightarrow HgI_4^{2-} + 2 OH^{-}$

Find the formula weight of the reactant if the formula weight of the product is $54 \ u$ and the percent atom economy is $75$. (in $u$)

What is the weight of carbon in $kg$ required to produce $270 \ kg$ of aluminum from bauxite by the Hall-Heroult process?

Mass of $NaOH$ required for formation of $100 \ mL$ of its decimolar solution is .............. $g$.

Which of the following reactions exhibits good atom economy according to the principles of green chemistry?