Here's why:

* Polar molecules have an uneven distribution of electrical charge. One end of the molecule is slightly positive, and the other end is slightly negative.

* Water molecules are highly polar, with the oxygen atom being slightly negative and the hydrogen atoms being slightly positive.

* Sugar molecules also have polar regions, with the oxygen atoms being slightly negative and the carbon and hydrogen atoms being slightly positive.

When sugar is added to water:

* The positive ends of water molecules are attracted to the negative ends of sugar molecules, and vice versa.

* These attractions break apart the sugar molecules and cause them to disperse evenly throughout the water, creating a solution.

In contrast, non-polar molecules, such as oil, do not dissolve in water because they lack these strong attractions.