The mass of urea required to make $2.5 \ kg$ of $0.25 \ molal$ aqueous solution is (in $g$)

The molarity of the solution obtained by mixing $50 \ mL$ of concentrated $H_2SO_4$ $(36 \ N)$ with $50 \ mL$ of water is .......... $M$.

The molecular weight of glucose is $180$. $A$ solution of glucose which contains $18 \ g$ per litre is ........... $molal$.

$20 \, mL$ of $0.5 \, M \, HCl$ is mixed with $30 \, mL$ of $0.3 \, M \, HCl$. The molarity of the resulting solution is $......... \, M$.

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 ........... $M$.

Density of $3 \ M$ $NaCl$ solution is $1.25 \ g/mL$. The molality of the solution is : (in $m$)