How many grams of $HCl$ will be present in $150 \ mL$ of its $0.52 \ M$ solution?

Some $CO_2$ gas was kept in a sealed container at a pressure of $1 \ atm$ and at $273 \ K$. This entire amount of $CO_2$ gas was later passed through an aqueous solution of $Ca(OH)_2$. The excess unreacted $Ca(OH)_2$ was later neutralized with $0.1 \ M$ of $40 \ mL$ $HCl$. If the volume of the sealed container of $CO_2$ was $x$,then $x$ is $............. \ cm^3$ $(nearest \ integer)$.
$[$Given : The entire amount of $CO_{2(g)}$ reacted with exactly half the initial amount of $Ca(OH)_2$ present in the aqueous solution.$]$

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?

$A$ container contains $4 \ g$ of $H_2$,$4 \ g$ of $He$,and a certain amount of $Ne$ at a certain temperature. What is the mass of $Ne$ required so that the partial pressure exerted by $Ne$ is equal to the partial pressure of $He$ (in $g$)?

One mole of methanol when burnt in excess of $O_2$ releases $723 \ kJ \ mol^{-1}$ of heat. If $1 \ mol$ of $O_2$ is used,what will be the amount of heat evolved in $kJ$?

In the following reaction sequence,the $\%$ yield for reaction $I$ is $60 \%$ and that of reaction $II$ is $50 \%$. The overall yield of the complete reaction is $..........\%$ [nearest integer].