How many grams of $BaCO_3$ are produced when excess $CO_2$ is passed through $0.205 \ mol$ of $Ba(OH)_2$?

If salicylic acid $(138 \text{ u})$ reacts with acetic anhydride $(102 \text{ u})$ to form aspirin $(180 \text{ u})$ and acetic acid $(60 \text{ u})$,calculate the percentage atom economy. (in $\%$)

If equal masses of methane $(CH_4)$ and hydrogen $(H_2)$ are mixed in an empty container at $25\,^oC$,what is the fraction of the total pressure exerted by hydrogen?

Dissolving $120 \ g$ of a compound (mol. wt. $60$) in $1000 \ g$ of water gave a solution of density $1.12 \ g/mL$. The molarity of the solution is ............ $M$.

If $100 \ mL$ of $1 \ N$ sulphuric acid were mixed with $100 \ mL$ of $1 \ M$ sodium hydroxide,the solution will be

$20.0 \ g$ 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? $(At. \ wt. \ of \ Mg = 24)$