The number of moles of $KCl$ in $1000 \ mL$ of $3 \ M$ solution is

What is mole fraction? Explain in brief.

Calculate the mass of urea $[NH_2CONH_2]$ required in making $2.5 \ kg$ of $0.25 \ m$ aqueous solution. (in $g$)

$3.0 \ g$ ethanoic acid in $50 \ g$ benzene has . . . . . . molality. (Atomic weights: $H=1, C=12, O=16$).

The mole fraction of a solvent in an aqueous solution of a solute is $0.8$. The molality (in $mol \ kg^{-1}$) of the aqueous solution is:

$25 \ mL$ of $3.0 \ M \ HNO_3$ are mixed with $75 \ mL$ of $4.0 \ M \ HNO_3$. If the volumes are additive,the molarity of the final mixture would be ......... $M$.