Question

When you run an electrical current through liquid water, the water molecules are split apart to form oxygen and hydrogen gas. The transfer of energy caused what kind of change to the water?

Answer 1

The answer is "chemical properties". The original water is split apart by the current
to form its constituent elements, hydrogen & oxygen. This is a chemical change, as
the original water is lost and new substances, H2 & O2, are produced.
Hope this answers your question.