Zona, the nutty professor, gathered the class one day for an experiment. Zona began, "I have in my hands a rock and a piece of wood. I am going to place them in this beaker of mysterious liquid, and you may observe what happens." Surprisingly, the rock floated and the wood sank! He turned to the class and said, "My question is: What is this mysterious liquid in the beaker?"

Do you know the answer?