Groundwater is also one of our most important sources of water for irrigation from septic tanks and toxic chemicals from underground storage tanks and leaky landfills ... Drinking contaminated groundwater can have serious health effects. If there is a leak, these contaminants can eventually make their way down
The process that is an example of a chemical change would be of ice turning into water when heated over a Bunsen Burner.
The mass of 1.20x10^25 atoms of Ca is 8000 grams
