The molarity of $0.2 \ N$ $Na_2CO_3$ solution will be (in $M$)

For the reaction $4FeCr_2O_4 + 8Na_2CO_3 + 7O_2 \rightarrow 8Na_2CrO_4 + 2Fe_2O_3 + 8CO_2$,what is the stoichiometric ratio of the products $Na_2CrO_4 : Fe_2O_3 : CO_2$?

If $0.4 \ g$ of $NaOH$ is present in $40 \ mL$ of solution,what will be the molarity and normality? (Molecular weight of $NaOH = 40$)

The molarity of pure water is ...... .

When $10 \ g$ of $90 \%$ pure limestone is heated, the approximate volume $($in $L$ $)$ of $CO_2$ liberated at $\text{STP}$ is:

For the combustion reaction of $1 \, mol$ of hydrocarbon $C_xH_{2y}$,the number of moles of $O_2$ required will be............