How many grams of ethanol are required to obtain $280 \ mL$ of dihydrogen gas at $S.T.P.$ by the reaction of $C_2H_5OH$ with $Na$ metal? (Molar mass of ethanol = $46 \ g/mol$)

Under the same conditions,how many $mL$ of $1 \ M \ KOH$ and $0.5 \ M \ H_2SO_4$ solution,respectively,when mixed to form a total volume of $100 \ mL$,produce the maximum rise in temperature?

How many milliliters of water must be added to $10 \, mL$ of $10 \, N \, HNO_3$ to convert it into $0.1 \, N \, HNO_3$?

How many litres of oxygen (at $STP$) are required for complete combustion of $39 \ g$ of liquid benzene?
(Atomic weights: $C=12, O=16, H=1$)

Calculate the approximate mass (in $g$) of $H_2S$ required for the following reaction when $15 \ L$ of oxygen at $STP$ reacts completely.
$2 H_2S_{(g)} + 3 O_{2(g)} \longrightarrow 2 SO_{2(g)} + 2 H_2O_{(g)}$
(molar mass of $H_2S = 34 \ g \ mol^{-1}$)

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 $u$)