How many grams of $CH_3OH$ should be added to water to prepare $150 \ mL$ solution of $2 \ M \ CH_3OH$?

$A$ solution contains $7.8 \ g$ of benzene $(C_6H_6)$ and $46.0 \ g$ of toluene $(C_6H_5CH_3)$. What is the mole fraction of benzene?

Increasing the temperature of an aqueous solution will cause

The molality of an aqueous solution of glucose is $1.0 \ m$. The mole fraction of glucose is approximately .....

$A$ commercially sold concentrated $HCl$ is $35 \%$ $HCl$ by mass. If the density of this commercial acid is $1.46 \ g/mL$,the molarity of this solution is $....M$.
(Atomic mass : $Cl = 35.5 \ amu, H = 1 \ amu$)

The concentration of $Ca^{2+}$ ions in a water sample is $0.0002 \ M$. What is the concentration of $Ca^{2+}$ in $ppm$ by weight-volume?