In the preceding question,the amount of $Na_2CO_3$ present in the solution is ............. $g$.

$20.0 \ g$ of a magnesium carbonate sample decomposes on heating to give carbon dioxide and $8.0 \ g$ magnesium oxide. What will be the percentage purity of magnesium carbonate in the sample? $(At. \ wt. \ of \ Mg = 24)$

$x$ grams of calcium carbonate was completely burnt in air. The weight of the solid residue formed is $28 \,g$. What is the value of $x$ (in grams)?

$A$ metal chloride contains $71\%$ chlorine by mass and has a vapor density of $50$. What is the atomic mass of the metal?

$8 \ g$ of $H_2$ and $256 \ g$ of $HI$ are in a $4 \ L$ flask. Calculate their active mass. $(H = 1 \ g \ mol^{-1}, I = 127 \ g \ mol^{-1})$

The mass percentage composition of dry air at sea level is approximately $N_2: 63 \%$, $O_2: 16 \%$, $Kr: 21 \%$. If the total pressure is $p \ atm$, calculate the partial pressure of each component respectively. (Molecular weights: $N_2 = 28, O_2 = 32, Kr = 84$)