The molarity of a solution obtained by mixing $750 \, mL$ of $0.5 \, M \, HCl$ with $250 \, mL$ of $2 \, M \, HCl$ will be $......... \, M$.

Calculate the mass of sodium acetate $(CH_3COONa)$ required to make $500 \ mL$ of a $0.375 \ M$ aqueous solution. The molar mass of sodium acetate is $82.0245 \ g \ mol^{-1}$. (in $g$)

The density of '$x$' $M$ solution ('$x$' molar) of $NaOH$ is $1.12 \ g \ mL^{-1}$. While in molality,the concentration of the solution is $3 \ m$ $(3 \ molal)$. Then '$x$' is.
(Given: Molar mass of $NaOH$ is $40 \ g \ mol^{-1}$)

$10.30 \; mg$ of $O_2$ is dissolved in $1 \; L$ of seawater with a density of $1.03 \; g/mL$. The concentration of $O_2$ in $ppm$ is:

$A$ sample of drinking water is found to be severely contaminated with chloroform $(CHCl_3)$,which is a suspected carcinogen. The level of contamination is $15 \ ppm$ (by mass). Calculate the molarity of chloroform in the water sample.

What is the molarity of a solution of $HCl$ which contains $49\%$ by weight of solute and whose specific gravity is $1.41$ (in $M$)?