The number of moles of a solute in its solution is $20$ and the total number of moles is $80$. The mole fraction of the solute is:

$x$ grams of water is mixed in $69 \ g$ of ethanol. The mole fraction of ethanol in the resultant solution is $0.6$. What is the value of $x$ in grams?

The volume of a solution changes with a change in temperature. How will the molality of the solution be affected by temperature? Give a reason for your answer.

Conc. $H_2SO_4$ has a density of $1.98 \ g/mL$ and is $98\%$ $H_2SO_4$ by weight. Its normality is ......... $N$.

Which among the following is a unitless physical quantity?

If $15 \ g$ of $NaOH$ is dissolved in water to make $250 \ mL$ of solution,find the molarity of this solution in $M$.