A solution containing 1.93 x 10⁻⁴ m caffeine in methanol was analysed by uv-vis spectrophotometry using a 4 cm cell, where 70% of the incident light was transmitted at the wavelength of maximum absorption (compared with a methanol blank). calculate the molar absorptivity (e) of caffeine at this wavelength (in units of dm3 mol⁻¹ cm⁻¹).
