30 g of sugar was mixed in 180 ml water in a vessel A, 40 g of sugar was mixed in 280 ml of water in vessel B and 20 g of sugar was mixed in 100 ml of water in vessel C. The solution in vessel B is:

The correct option is less sweet than that in C.

To determine which solution is sweeter or less sweet, we need to compare the concentration of sugar in each vessel. The sweetness of a sugar solution depends on the ratio of the mass of sugar to the volume of water. A higher sugar-to-water ratio indicates a higher concentration of sugar, which means a sweeter solution.

Let us calculate the concentration (sugar per ml of water) for each vessel:

For vessel A:
Mass of sugar = 30 g
Volume of water = 180 ml
Concentration in A = $\frac{30}{180}$ = $\frac{1}{6}$ ≈ 0.167 g/ml

For vessel B:
Mass of sugar = 40 g
Volume of water = 280 ml
Concentration in B = $\frac{40}{280}$ = $\frac{1}{7}$ ≈ 0.143 g/ml

For vessel C:
Mass of sugar = 20 g
Volume of water = 100 ml
Concentration in C = $\frac{20}{100}$ = $\frac{1}{5}$ = 0.200 g/ml

Now, let's compare the concentrations:
Concentration in C ($\frac{1}{5}$ or 0.200 g/ml) is greater than concentration in A ($\frac{1}{6}$ or 0.167 g/ml), which is greater than concentration in B ($\frac{1}{7}$ or 0.143 g/ml).

Since the concentration of sugar in vessel B (0.143 g/ml) is lower than the concentration of sugar in vessel C (0.200 g/ml), the solution in vessel B is less sweet than the solution in vessel C.