Students in a biology class thought that salt water would affect the movements of planaria.
They put 25 planaria in salt water and
recorded their observations.
Which flaw was present
in the design of their
experiment?

2h2o2--> 2h2o + o2

this reaction is of the spontaneous decomposition of hydrogen peroxide down into water and oxygen.

add 2 molecules of hydrogen peroxide and 2 molecules of water. since oxygen is naturally diatomic, the total number of atoms of each element is now the same on both sides of the equation so it is balanced.

this may not be entirely correct but let me know.