What is the volume occupied by $2.5 \ mol$ of ammonia gas at $\text{STP}$ (in $dm^3$)?

What is the percentage atom economy during the conversion of reactant to product if the formula weight of reactants is $246 \ u$ and that of the product is $123 \ u$ (in $\%$)?

If $1/2 \text{ mole of oxygen reacts with aluminum to form } Al_2O_3, \text{ the mass of aluminum metal consumed in the reaction is } ..... \text{ g. } (Al=27)$

How many moles of potassium chlorate $(KClO_3)$ must be heated to produce $22.4 \text{ L}$ of oxygen gas at $STP$?

$28 \ g$ $KOH$ is required to completely neutralize $CO_2$ produced on heating $60 \ g$ of impure $CaCO_3$. The percentage purity of $CaCO_3$ is approximately (molar masses of $KOH$ and $CaCO_3$ are $56$ and $100 \ g \ mol^{-1}$, respectively).

The mass of sodium acetate $(CH_3COONa)$ required to prepare $250 \ mL$ of $0.35 \ M$ aqueous solution is . . . . . . $g$. (Molar mass of $CH_3COONa$ is $82.02 \ g \ mol^{-1}$)