Which is a compound? (need explanation please) I need this answer asap (as soon as possible) please

a. Kr

b. O2

c. Cl2

D. CuF2

Which of the following ocean acidification? are the most likely side effects of a ph less than 7.0 in the ocean b. more metal salts altering the ocean chemistry c. dissolution of the shells of marine organisms d. both a & b e. all of the above.

In an investigation that uses the scientific method, which step immediately follows making a hypothesis? o summarizing the results o asking a question o making observations designing an experiment mark this and retum save and exit next submit

An atom of which element reacts with an atom of hydrogen to form a bond with the greatest degree of polarity ?