Achemical reaction is a process by which one or more substances transform into different substances via a chemical change. sometimes, chemical reactions exhibit evidence that can be easily observed when they occur. part a which changes are evidence of a chemical reaction?

Indication/Proof: Two transparent solutions are combined and form a murky substance, A water beaker is hot to touch when applying detergent powder, Bubble forming applied to acid on chalk.

Not proof: bubbles that form in a pot of boiling water, water condensation.

we can conclude that the melting point of table salt is above room temperature (it's actually 801 deg c). the melting point of mercury must be below room temperature (- 39 deg c).

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.