Calculate the percent atom economy when a product of formula weight $175 \ u$ is obtained in a chemical reaction using $225 \ u$ formula weight reactant. (in $\%$)

What is the value of $w$ (mass of solute in grams) required to prepare a definite volume of a standard solution of known normality $(N)$?
[$N = \text{normality}$,$E = \text{equivalent weight}$,$V = \text{volume of solution in } mL$]

If an $LPG$ cylinder contains a mixture of butane and isobutane,what is the amount of oxygen required for the combustion of $1 \ kg$ of this mixture in $kg$?

Three solutions of $HCl$ having normalities $12 \ N$,$6 \ N$,and $2 \ N$ are mixed to obtain a solution of $4 \ N$ normality. Which among the following volume ratios is incorrect for the above mixture?

The Molarity $(M)$ of an aqueous solution containing $5.85 \ g$ of $NaCl$ in $500 \ mL$ water is :
(Given : Molar Mass $Na: 23$ and $Cl: 35.5 \ g \ mol^{-1}$ )

What volume of $0.8 \ M$ solution contains $0.1 \ mole$ of the solute? (in $mL$)