The molarity of a $NaOH$ solution prepared by dissolving $4 \ g$ of it in $250 \ mL$ of water is: (in $M$)

Volume of $3 \ M \ NaOH$ (formula weight $40 \ g \ mol^{-1}$) which can be prepared from $84 \ g$ of $NaOH$ is $ . . . . . . \times 10^{-1} \ dm^3$.

$X$ litre of carbon monoxide is present at $STP$. It is completely oxidized to $CO_2$. The volume of $CO_2$ formed is $11.207 \ L$. What is the value of $X$ in litres?

For the given series of reactions:
$NH_{3(g)} + O_{2(g)} \rightarrow NO_{(g)} + H_2O_{(l)}$
$NO_{(g)} + O_{2(g)} \rightarrow NO_{2(g)}$
To obtain the maximum mass of $NO_2$ from a given mass of a mixture of $NH_3$ and $O_2$,the ratio of the mass of $NH_3$ to $O_2$ should be:

$510 \ mg$ of a liquid on vaporisation in Victor Mayer's apparatus displaces $510 \ cm^3$ of dry air (at $NTP$). The molecular weight of the liquid is:

Concentrated sulfuric acid is $95\%$ by weight and its density is $1.8 \ g \ cm^{-3}$. What volume of concentrated acid in $cm^3$ is required to prepare $4 \ L$ of $0.4 \ M \ H_2SO_4$ solution (in $.7$)?