How many liters of $CO_2$ gas are released at $STP$ upon the complete decomposition of $9.85 \ g$ of $BaCO_3$ (Atomic mass of $Ba = 137$)?

Find the formula weight of the reactant if the formula weight of the product is $54 \ u$ and the percent atom economy is $75$. (in $u$)

The reaction of $1 \ mol$ of magnesium nitride with excess water gives:

How many grams of $NaOH$ are required to neutralize $12.2 \ g$ of benzoic acid (in $g$)?

What volume of $10 \, M \, HCl$ is required to prepare $2.00 \, L$ of $5 \, M \, HCl$ by dilution with water (in $, L$)?

Galena (an ore) is partially oxidized by passing air through it at high temperature. After some time,the passage of air is stopped,but the heating is continued in a closed furnace such that the contents undergo self-reduction. The weight (in $kg$) of $Pb$ produced per $kg$ of $O_2$ consumed is $. . . . .$ (Atomic weights in $g \ mol^{-1}: O = 16, S = 32, Pb = 207$)