Why does a person's heart rate increase during exercise? (1) less oxygen is needed.(2) more oxygen is needed. (3) less carbon dioxide is needed. (4) more carbon dioxide is needed

Asample of silver (with work function ? = 4.52 ev) is exposed to an ultraviolet light source (? = 200 nm), which results in the ejection of photoelectrons. what changes will be observed if: silver is replaced with copper (? = 5.10 ev) more photoelectrons ejected no photoelectrons are emitted fewer photoelectrons ejected more energetic photoelectrons (on average) less energetic photoelectrons (on average)

When water dissociates, each water molecule splits into a hydroxide ion and a) h 3 o + b) a hydrogen atom c) a hydrogen ion d) h 2 o e) oh —

What is the lowest number energy level where a d sublevel is found