If $22 \ g$ of benzene $(C_6H_6)$ is dissolved in $122 \ g$ of carbon tetrachloride $(CCl_4)$,calculate the mass percentage of benzene. (in $\%$)

Dissolving $120 \ g$ of urea (mol. wt. $60$) in $1000 \ g$ of water gave a solution of density $1.15 \ g / mL$. The molarity of the solution is (in $M$)

$25.3 \ g$ of sodium carbonate,$Na_2CO_3$ is dissolved in enough water to make $250 \ mL$ of solution. If sodium carbonate dissociates completely,the molar concentration of sodium ions,$Na^{+}$,and carbonate ions,$CO_3^{2-}$,are respectively:
(Molar mass of $Na_2CO_3 = 106 \ g \ mol^{-1}$)

The weight percent of sucrose (formula weight $= 342 \, g \, mol^{-1}$) in an aqueous solution is $3.42$. The density of the solution is $1 \, g \, mL^{-1}$. The concentration of sucrose in the solution in $mol \, L^{-1}$ is

$A$ mixture of alcohol and water contains $54 \%$ water by mass. What is the mole fraction of ethanol?

The number of moles of $KCl$ in $1000 \ mL$ of $3 \ M$ solution is