The diagram shows a heating curve for water. A graph labeled heating curve for water with heat in joules on the x axis and temperature in degrees celsius on the y axis labeled 40 to 110. There is a line from the origin up to 100 degrees labeled X. There is a horizontal line from X to Y at 100 degrees. There is a diagonal line from Y up to Z at 110 degrees. Which statement best describes what is happening at segment W-X? Water is absorbing heat. Water is releasing heat. A liquid is changing to a gas. A gas is changing to a liquid.