What is the pH of a solution that is 100x more acidic than a solution with a pH of 5?

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)

Who is better, messi or cristiano, i need this for a chemistry class. asap

If 1.63 times 10 negative 4 of helium dissolves in 100.0g of water, what is the concentration in parts per million