For the gaseous reaction $H_2 + Cl_2 \rightarrow 2HCl$,if $40 \ mL$ of hydrogen reacts with chlorine,the volume of chlorine required and the volume of $HCl$ formed are respectively:

$250 \ mL$ of a sodium carbonate solution contains $2.65 \ g$ of $Na_2CO_3$. If $10 \ mL$ of this solution is diluted to $1 \ L$, what is the concentration of the resultant solution (in $M$)?

Suppose a cooking gas cylinder contains $11.2 \, kg$ of isobutane. The thermochemical equation for the combustion of butane is given below:
$C_4H_{10}(g) + \frac{13}{2} O_2(g) \to 4CO_2(g) + 5H_2O(\ell); \Delta H = -2658 \, kJ$
If a family requires $15000 \, kJ$ of energy per day for cooking,how many days will the cylinder last?

Volume of air required to completely burn $10 \ L$ of $C_2H_4$ is ................ $L$ (assume all volumes are measured at the same temperature and pressure,and air contains $20\%$ oxygen by volume).

What ratio by mass of $Ne$ and $CH_4$ should be mixed so that the partial pressure exerted by each gas is the same?

Calculate the number of $Cl^{-}$ ions in $222 \ g$ anhydrous calcium chloride? (At. mass $Ca=40, Cl=35.5$)