$200 \ mL$ of a solution contains $5.85 \ g$ dissolved sodium chloride. The concentration of the solution will be .......... $molar$ $(Na = 23; Cl = 35.5)$.

$A$ sample of drinking water was found to be severely contaminated with chloroform,$CHCl_{3}$,supposed to be carcinogenic in nature. The level of contamination was $15 \ ppm$ (by mass).
$(i)$ Express this in percent by mass.
$(ii)$ Determine the molality of chloroform in the water sample.

$A$ $5.2$ molal aqueous solution of methyl alcohol,$CH_3OH$,is supplied. What is the mole fraction of methyl alcohol in the solution?

The density of a $2.05 \ M$ solution of acetic acid $(CH_3COOH)$ in water is $1.02 \ g \ mL^{-1}$. The molality of the solution is ......... $mol \ kg^{-1}$.

$50 \ g$ of a substance is dissolved in $1 \ kg$ of water at $90^{\circ} C$. The temperature is reduced to $10^{\circ} C$. The density is increased from $1.1 \ g \ cm^{-3}$ to $1.15 \ g \ cm^{-3}$. What is the $\%$ change of molarity of the solution?

Molarity of a solution prepared by dissolving $75.5 \ g$ of pure $KOH$ in $540 \ mL$ solution is .......... $M$