What is the volume (in $mL$) of $20$ vol $H_2O_2$ required to completely react with $500 \ mL$ of $0.02 \ M$ acidified $KMnO_4$ solution?

One and a half mole of oxygen combine with aluminium to form $Al_2O_3$. The weight of aluminium metal used in this reaction is .............. $g$ (Atomic weight of $Al = 27$).

If a rocket runs on a fuel $(C_{15}H_{30})$ and liquid oxygen,the weight of oxygen required and $CO_{2}$ released for every litre of fuel respectively are: (Given: density of the fuel is $0.756 \ g/mL$)

When $CO_2$ is bubbled through $0.205 \ mol$ of $Ba(OH)_2$,how many grams of $BaCO_3$ will be produced?

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 $Ba = 137$,$C = 12$,$O = 16$)

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 $\%$)