Compare an electrically neutral atom of oxygen and an isotope of oxygen. in own words

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)

If you have 5.25 grams of methane (ch4), how many grams of co2 will you produce ?

Who discovered a pattern to the elements in 1869?