How many electrons would need to be added to fill the outermost energy level of hydrogen? of oxygen?

This graph gives information on changes in sea ice extent in the arctic ocean over a 30-year span. the overall trend shows in the ice extent. to address the trend, scientists need to ask themselves, one direct consequence of the trend is that

Which step in naming unsaturated hydrocarbons is used for alkenes but not alkynes

How would the number of moles (n) of o2 change if the atmospheric pressure doubled but all other variables stayed the same