Air with less than 19.5% oxygen cannot support human life. How many moles of oxygen would the caisson if the percent of oxygen in the air dropped to 19.4%.

its first and third is your answer i did the qustion the fourth isnt right

the answer is:  

line graphs show patterns in data with variables that change over time; whereas, circle graphs show data as parts out of a whole (such as out of 100%).