For a very diluted solution,the preferred concentration unit is:

$A$ solution containing $200 \ mL$ of $0.5 \ M$ $KCl$ is mixed with $50 \ mL$ of $19 \% \ w/v$ $MgCl_2$ and the resulting solution is diluted $8$ times. What is the molarity of the chloride ion in the final solution?

When $100 \ mL$ of $0.3 \ N$ $HCl$ solution is mixed with $200 \ mL$ of $0.6 \ N$ $H_2SO_4$ solution,what is the normality of $H_2SO_4$ in the final mixture?

Sea water,which can be considered as a $6 \ M$ solution of $NaCl$,has a density of $2 \ g \ mL^{-1}$. The concentration of dissolved oxygen $(O_2)$ in sea water is $5.8 \ ppm$. Then the concentration of dissolved oxygen $(O_2)$ in sea water is $x \times 10^{-4} \ m$. $x = ............$ $(Nearest \ integer)$
Given: Molar mass of $NaCl$ is $58.5 \ g \ mol^{-1}$. Molar mass of $O_2$ is $32 \ g \ mol^{-1}$.

Calculate the mass of urea $(NH_2CONH_2)$ required in making $2.5 \, kg$ of $0.25 \, \text{molal}$ aqueous solution.

What is the molarity of a $1 \ L$ solution of $93\% \ (w/v)$ $H_2SO_4$ (in $M$)? The density of the solution is $1.84 \ g/mL$.