Many metal atoms give off a distinct colour when heated. This colour can be used to identify the atom in a solution or a powder. Below are a set of elements flame tested at the Melbourne Forensic Laboratories.

Residents from a rural community complained that the water tasted bad and many were hospitalised with headaches and severe stomach cramps. A sample of the water was tested at the laboratories and the results shown on the right.

What does the flame test of the sample reveal?
Many residents blamed one of two power plants for the contaminated water.