What is $\Delta n$ for the combustion of $1 \ mole$ of benzene,when both the reactants and the products are in the gaseous state at $298 \ K$?

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 $u$)

$A$ mixture of $CaCl_{2}$ and $NaCl$ weighing $4.44 \ g$ is treated with sodium carbonate solution to precipitate all the $Ca^{2+}$ ions as calcium carbonate. The calcium carbonate so obtained is heated strongly to get $0.56 \ g$ of $CaO$. The percentage of $NaCl$ in the mixture (atomic mass of $Ca=40$) is

If the reduction of a sample of $Cu_2O$ yields $1.27 \, g$ of $Cu$,then how many grams of oxygen must be present in it?

$1.0 \ g$ of pure calcium carbonate was found to require $50 \ mL$ of dilute $HCl$ for complete reaction. The strength of the $HCl$ solution is given by ........ $N$.

$A$ bottle of cold drink contains $200 \, mL$ of liquid with $0.1 \, M$ $CO_2$. If $CO_2$ behaves ideally,what will be the volume of $CO_2$ gas at $STP$ in the cold drink solution (in $, L$)?