If the mole fraction of ethanol in a solution made by mixing $x \ g$ of water and $69 \ g$ of ethanol is $0.6$,then $x = \dots \dots \dots \dots$

$A$ $6.50$ molal solution of $KOH$ $(aq.)$ has a density of $1.89 \ g \ cm^{-3}$. The molarity of the solution is .......... $mol \ dm^{-3}$.
(Round off to the Nearest Integer).
[Atomic masses: $K = 39.0 \ u, O = 16.0 \ u, H = 1.0 \ u$]

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

The concentration of an aqueous solution of $0.01 \ M \ CH_3OH$ is very nearly equal to which of the following?

Calculate the mole fraction of urea in an aqueous solution of $1 \ m$ urea $(NH_2CONH_2)$.

$A$ solution is prepared by dissolving $24.5 \ g$ of sodium hydroxide in distilled water to give $1 \ L$ solution. The molarity of $NaOH$ in the solution is (Given that molar mass of $NaOH = 40.0 \ g \ mol^{-1}$) (in $M$)