Water is considered a polar molecule because
a. it has partial positive and negative charges at each end
b. it expands when it freezes
c. it dissolves solutes

The question is asking for the reason why water is considered a polar molecule. The correct option is A. Water molecule is a polar molecule because it has one side which is positively charged and the other side is negatively charged. Each molecule of water has two hydrogen atom and one oxygen atom. The slight negative charge near the oxygen atom attract nearby hydrogen atoms from water and the slightly positive charge of the hydrogen atom attract oxygen atom. The attraction set up by these charges are responsible for the polarity of water molecules.