$A$ solution is obtained by mixing $400 \ g$ of $25 \%$ solution and $600 \ g$ of $40 \%$ solution by mass. What is the mass percentage of the resulting solution (in $\%$)?

$A$ litre of seawater (which weighs $1030 \ g$) contains $6 \times 10^{-3} \ g$ of dissolved oxygen. The concentration of dissolved oxygen in $ppm$ is:

The mole fraction of urea in an aqueous urea solution containing $900 \text{ g}$ of water is $0.05$. If the density of the solution is $1.2 \text{ g cm}^{-3}$,the molarity of the urea solution is . . . . . (Given data: Molar masses of urea and water are $60 \text{ g mol}^{-1}$ and $18 \text{ g mol}^{-1}$,respectively)

To prepare a solution of concentration $0.03 \ g/mL$ of $AgNO_3$,what amount of $AgNO_3$ should be added in $60 \ mL$ of solution?

If the density of a $2 \ M$ solution of ethylene glycol in water is $1.11 \ g/mL$, the molality (in $m$) of the solution is approximately

An aqueous solution of alcohol contains $18 \ g$ of water and $414 \ g$ of ethyl alcohol. The mole fraction of water is