Which of the following represents an element ? H2O H2 NaCl CaCO3

Alarge marble is dropped in a graduated cylinder with 35ml of water in it.the water level increases to 49ml.what is the volume of the marble

List four observations that indicate that a chemical reaction may be taking place

The msds for glacial acetic acid says that it is a flammable liquid that can severely burn any human tissue it comes in contact with. it reacts with bases, various metals, and strong oxidizing agents. its vapors can form explosive mixtures with air.