Calculate the mole fraction of ethylene glycol $(C_{2}H_{6}O_{2})$ in a solution containing $20\%$ of $C_{2}H_{6}O_{2}$ by mass.

$x \ g$ 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?

$A$ solution is prepared by adding $2 \ g$ of $X$ to $1 \ mole$ of water. Mass percent of $X$ in the solution is $............. \ \%$

$10 \, mL$ of $2 \, M \, NaOH$ solution is added to $200 \, mL$ of $0.5 \, M \, NaOH$ solution. What is the final concentration? $............ \, M$

Explain $\% \, w/V$ and $\% \, w/w$ in brief.

Two solutions of a substance are mixed as follows: $480 \ mL$ of $1.5 \ M$ first solution + $520 \ mL$ of $1.2 \ M$ second solution. The molarity of the final solution will be ............. $M$.