$2 \ g$ of substance $A$ is added to $18 \ g$ of water to form a solution. Calculate the mass percentage of the solute. (in $\%$)

The mole fraction of a solute in a $1$ molal ethanolic solution is:

When $1.04 \ g$ of $BaCl_2$ is dissolved in $10^5 \ g$ of water,what will be the concentration of the solution in $ppm$?

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 $\%$)

$25 \ g$ of a solute of molar mass $250 \ g \ mol^{-1}$ is dissolved in $100 \ mL$ of water to obtain a solution whose density is $1.25 \ g \ mL^{-1}$. The molarity and molality of the solution are respectively

The $ppm$ level of $F^{-}$ in a $500 \ g$ sample of a toothpaste containing $0.2 \ g$ $F^{-}$ is: