What is the percent atom economy if the formula weight of reactants and the formula weight of products are $45 \ u$ and $35 \ u$ respectively (in $\%$)?

Commercial concentrated sulfuric acid is $95\% $ $H_2SO_4$ by weight. If the density of this commercial acid is $1.834 \ g \ cm^{-3}$,the molarity of this solution is ....... $M$.

What will be the weight of lime $(CaO)$ obtained by heating $300 \ kg$ of $90\%$ pure limestone $(CaCO_3)$?

Equal masses in grams of $H_2$, $N_2$, $Cl_2$, and $O_2$ are enclosed in cylinders separately. If these gases expand isothermally and reversibly by $10 \ dm^3$ at $300 \ K$, the work done by the gas is maximum for:

Volume of water needed to mix with $10 \ mL$ of $10 \ N \ HNO_3$ to get $0.1 \ N \ HNO_3$ is ............ $mL$.

The volumes of two $HCl$ solutions $A$ (Normality $= 0.5 \ N$) and $B$ (Normality $= 0.1 \ N$) to be mixed for preparing $2 \ L$ of $0.2 \ N \ HCl$ are: