arsenic
Nitrogen group element, any of the chemical elements that constitute Group 15 (Va) of the periodic table. The group consists of nitrogen (N), phosphorus (P), arsenic (As), antimony (Sb), bismuth (Bi), and moscovium (Mc).
B because theyre in order of the number of protons
The Use of nitrogen fertilizers near the lake is your answer.
By examining the tree bark and recording it’s properties. I would note if the cells move and duplicate, I would also note any living organisms which lay on the surface