Can someone please answer these 2 questions for me ? 1. How many O elements(s) is (are) there in water?

2. How do you know the number of H and O elements in water?

What sentence best supports the statement that hormones are involved in the regulation of homeostasis? a. the hormone erythropoeitin increases the production of red blood cells when oxygen levels are low. b. the hormone oxytocin promotes labor contractions of the uterus during childbirth. c. the hormone melatonin induces sleep and its production is slowed by exposure to light. d. the hormone cortisol suppresses the immune system and is produced when the body is under stress.

What substance is the most acidic. lemon juice. tomato juice. sodium hydroxide. water

Fill in the blank with the best word to complete the sentence. white blood cells protect against and aid in blood clotting when injuries are sustained.