Three solutions of $HCl$ having normalities $12 \ N$,$6 \ N$,and $2 \ N$ are mixed to obtain a solution of $4 \ N$ normality. Which among the following volume ratios is incorrect for the above mixture?

Volume of $0.1 \, M$ $H_2SO_4$ required to neutralize $30 \, mL$ of $0.2 \, N$ $NaOH$ is......$mL$

What volume of $CO_2$ at $STP$ is obtained by thermal decomposition of $20 \ g$ $KHCO_3$? [Atomic weight of $K = 39$]
$2KHCO_{3(s)} \to K_2CO_{3(s)} + CO_{2(g)} + H_2O_{(g)}$

When a hydrated salt,$Na_2SO_4 \cdot nH_2O$,is heated,it loses $56\%$ of its weight and becomes anhydrous. What is the approximate value of $n$?

$A$ car airbag is inflated by $N_2$ produced during rapid decomposition of $NaN_{3(s)}$. What will be the pressure of the inflated airbag if $130 \ g$ of $NaN_3$ is used (in $atm$)? The volume of the airbag is $10 \ L$ $(T = 300 \ K, R = 0.082 \ L \ atm \ K^{-1} \ mol^{-1})$.

$x \ mg$ of pure $HCl$ was used to make an aqueous solution. $25.0 \ mL$ of $0.1 \ M$ $Ba(OH)_2$ solution is used when the $HCl$ solution was titrated against it. The numerical value of $x$ is . . . . . . $\times 10^{-1}$. (Nearest integer)
Given: Molar mass of $HCl$ and $Ba(OH)_2$ are $36.5$ and $171.0 \ g \ mol^{-1}$ respectively.