In the cores of extremely hot red giants, nuclear reactions convert helium to <u>carbon</u>.
A red giant star is a dying star in the last stages of stellar evolution. In the main sequence stage stars convert hydrogen into helium through nuclear fusion.
As stars in the main sequence stage slowly converts their core from hydrogen to helium the fusion continues to create a shell and soon the Helium core begins to shrink, and visible of the star change. The star becomes a red giant.
<em><u>In the red giant core the nuclear reactions convert helium into carbon. This happens when the temperature reaches 100 million K, and the nuclear fusion of He to Carbon begins, creating carbon and releasing energy.</u></em>
You could use a scale to measure the mass as well as a cup to hold the water. If you were comparing the two, you should also probably use a graduated cylinder to get the same amount of each type of water.