$A$ $6.50$ 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: $K = 39.0 \ u, O = 16.0 \ u, H = 1.0 \ u$]

Explain $\% \ V/V$ in brief.

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 $32 \ g \ mol^{-1}$.

$300 \ g$ of $25\%$ solution and $400 \ g$ of $40\%$ solution are mixed by weight. Calculate the percentage of the solute by weight in the final mixture. (in $\%$)

If the concentration of $Al^{3+}$ in an aqueous solution of $Al_2(SO_4)_3$ is $0.28 \ M$,then the concentration of $(SO_4)^{2-}$ ion is ........... $M$.

At a constant temperature,if the molarity $(M)$ and molality $(m)$ of an aqueous solution of urea are equal,which of the following options is correct for the density $(d)$ of the solution?