$10 \ g$ of a solute is dissolved in $90 \ g$ of a solvent. Its mass percent in solution is

Explain parts per million (ppm) in brief.

The amount of water that should be added to $500 \, mL$ of $0.5 \, N$ solution of $NaOH$ to give a concentration of $10 \, mg$ per $mL$ is (in $, mL$)

Calculate the molarity of a solution of ethanol in water in which the mole fraction of ethanol is $0.040$ (assume the density of water to be $1 \, g/mL$).

Define the term solution. How many types of solutions are formed? Write briefly about each type with an example.

$A$ 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 $\%$)?