Consider Three 1-L Flasks at the Same Temperature and Pressure

Consider three 1-L flasks at the same temperature and pressure. Flask A contains CO gas, flask B contains N₂ gas, and flask C contains O₂ gas.Which contains the lowest density?

A) flask A
B) flask B
C) flask C
D) All are the same.
E) Two of the flasks contain gases at the same density.