All of the following are evidence that a chemical reaction has occurred except
a. color change
b. formation of a precipitate
c. bubbles of gas
d. all of the above are evidence of a chemical reaction

primary succession begins with a bare rock and ends with a forest secondary succession begins after a natural disaster where there is a temporary setback after a forest fire or local destruction, but the surrounding area can fill in

nucleic acid molecules are incredibly complex, containing the code that guarantees the four different nucleotide units comprise dna, the nucleic acid of interest to the genealogist. and one of four nitrogen-containing molecules called nucleotides