The vapour density of a gas is $11.2$. The volume occupied by $11.2 \ g$ of this gas at $N.T.P.$ is ................ $L$

$0.53 \ g$ of $Na_2CO_3$ has been dissolved in $100 \ mL$ of a sodium carbonate solution. The normality of the solution will be

In a metal deficient oxide sample,$M_X Y_2 O_4$ ($M$ and $Y$ are metals),$M$ is present in both $+2$ and $+3$ oxidation states and $Y$ is in $+3$ oxidation state. If the fraction of $M^{2+}$ ions present in $M$ is $\frac{1}{3}$,the value of $X$ is. . . . . . .

The conversion of oxygen to ozone occurs to the extent of $15\%$ only. The mass of ozone that can be prepared from $67.2 \ L$ of oxygen at $1 \ atm$ and $273 \ K$ will be ............ $g$.

An iron alloy contains $54.7\%$ iron and has a density of $8.17 \, g \, cm^{-3}$. What is the number of iron atoms in an alloy block of dimensions $10 \, cm \times 15 \, cm \times 20 \, cm$?

When excess $CO_2$ is passed through a solution containing $0.205 \ mol$ of $BaCO_3$,what is the mass of $Ba(HCO_3)_2$ formed in grams?