URGENT I AM BEING TIMED. I will mark you brainliest Please help with question 20.

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)

Which part of earth’s surface receives the most direct rays from the sun? a) equator b) ocean c) poles d) mountains

What produces wave a)sound b) heats c)transfer of energy d)vibrations