If a mixture of $340 \ g$ of $N_2$ and $H_2$ in the stoichiometric ratio yields $20\%$ $NH_3$ by mass,what is the mass of $NH_3$ produced in $g$?

How many $g$ of $KOH$ are required to completely neutralize $12.6 \, g$ of $HNO_3$?

$23 \ g$ of $Na$ metal reacts with ethanol to produce which of the following?

$10 \ g$ of a piece of marble $(CaCO_3)$ was put into excess of dilute $HCl$ acid. When the reaction was complete,$1120 \ mL$ of $CO_2$ was obtained at $STP$. The percentage of pure $CaCO_3$ in the marble is $............ \%$.

$A$ gas weighing $2.4 \ g$ has a vapor density of $11.2$. What is its volume in $L$ at $STP$?

What is the volume of $CO_2$ in liters produced at $STP$ by the complete decomposition of $9.85 \ g$ of $BaCO_3$? (Atomic mass of $Ba = 137$,$C = 12$,$O = 16$)