How many grams of ethanol must be added to $1.0 \ kg$ of water to have a mole fraction of ethanol equal to $0.2$?

$4.5 \ g$ of compound $A$ $(MW = 90)$ was used to make $250 \ mL$ of its aqueous solution. The molarity of the solution in $M$ is $x \times 10^{-1}$. The value of $x$ is ............ (Rounded off to the nearest integer)

In $500 \ mL$ of $0.2 \ M \ NaCl$ solution,$1500 \ mL$ of $0.4 \ M \ MgCl_2$ solution is mixed. The only incorrect final concentration of ion is (assume volume to be additive)

The molality of an aqueous solution of any solute having a mole fraction of $0.25$ is . . . . . . . (in $m$)

What is the approximate molality of $10 \% (w/w)$ aqueous glucose solution (in $m$)? (Molar mass of glucose $= 180 \ g \ mol^{-1}$)

Molality of $30 \% \ w/w$ aqueous solution of $NaOH$ is . . . . . . . (in $m$)