demonstration in which a scientist combined two substances in a sealed container and analyzed the results. The ending substances did not look the same as the starting substances.

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

Suppose a lab group reports a ppercent yield of sand of 105. is it really possible to collect more sand than was originally represented? what is the possible explanation for the extra product?