The quantum yield for CO(g) production in the photolysis of gaseous acetone is unity for wavelengths between 250 and 320 nm. After 20.0 min of irradiation at 313 nm, 18.4 cm³ of CO(g) (measured at 1008 Pa and 22°C ) is produced. Calculate the number of photons absorbed, and the absorbed intensity in J s^–1.