Which is a characteristic of a physical change? (2 points) the chemical bonds in the substance are unchanged. the change cannot be seen. the molecules all move at the same speed. the substance has reacted with another substance.

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.

b.final