What is the difference between an amoeba and a hydra?

Asingle atom of an element has 21 neutrons, 20 electrons, and 20 protons. which element is it? ok o z

6. using 3 – 4 sentences explain (in your own words) why water expands when it freezes? 7. using your knowledge of colligative properties explain whether sodium chloride or calcium chloride would be a more effective substance to melt the ice on a slick sidewalk. use 3 – 4 sentences in your explanation.

How does carbon monoxide pose the greatest threat to humans? a. it can be produced by wood fires. b. it can be produced by home furnaces. c. it is produced by acid rain. d. it is produced by modern automobiles.