What amount of oxygen is used at $S.T.P$ to obtain $9 \ g$ water from a sufficient amount of hydrogen gas (in $dm^3$)?

Concentrated aqueous sulphuric acid is $98\% \ H_2SO_4$ by mass and has a density of $1.80 \ g \ mL^{-1}$. The volume of acid required to make $1 \ L$ of $0.1 \ M \ H_2SO_4$ solution is ........ $mL$.

Phosphoric acid $(H_3PO_4)$ is a tribasic acid and one of its salts is sodium dihydrogen phosphate $(NaH_2PO_4)$. What volume of $1 \ M$ $NaOH$ solution should be added to $12 \ g$ of sodium dihydrogen phosphate (mol. wt. $120$) to exactly convert it into trisodium phosphate $(Na_3PO_4)$? (Answer in $mL$)

$A$ solution of sulfuric acid contains $80\%$ $H_2SO_4$ by weight and has a specific gravity of $1.71$. What is its normality?

If $1 \, L$ of $N_2$ and $7/8 \, L$ of $O_2$ gases are mixed at the same temperature and pressure,what is the relationship between their masses in the mixture?

The molecular formula of a commercial resin used for exchanging ions in water softening is $C_8H_7SO_3^- Na^+$ $(Mol. \ wt. 206)$. What would be the maximum uptake of $Ca^{2+}$ ions by the resin when expressed in mole per gram resin?