Correct Answer: C
Explanation:
The correct option is '3'.
Molarity of acetic acid solution = 2.05 M
Therefore the number of moles of acetic acid in 1 L solution = 2.05 mol
mass of acetic acid in 1 L solution = no. of moles x molar mass = 2.05 mol x 60 g mol-1 = 123 g
Note: molar mass of acetic acid is 60 g mol-1
Density, d = mass of solution / volume of solution
Hence:
mass of solution = density x volume of solution = 1.02 g mL-1 x 1000 mL = 1020 g
mass of solvent = mass of solution - mass of solute = 1020 - 123 = 897 g = 0.897 kg
molality, m = no. of moles / mass of solvent (in Kg) = 2.05 mol / 0.897 kg = 2.285 mol kg-1