$A$ mixture of camphor in air is an example of which type of solution?

If a substance $A$ dissolves in a solution of a mixture of $B$ and $C$ with their respective number of moles as $n_A, n_B$ and $n_C$,the mole fraction of $C$ in the solution is:

$25 \ g$ of a solute of molar mass $250 \ g \ mol^{-1}$ is dissolved in $100 \ mL$ of water to obtain a solution whose density is $1.25 \ g \ mL^{-1}$. The molarity and molality of the solution are respectively

$4.5 \ g$ of compound $A$ $(MW = 90)$ was used to make $250 \ mL$ of its aqueous solution. The molarity of the solution in $M$ is $x \times 10^{-1}$. The value of $x$ is ............ (Rounded off to the nearest integer)

Calculate the mole fraction of urea in an aqueous solution of $1 \ m$ urea $(NH_2CONH_2)$.

What is molarity?