2.3 Alumina (Al2O3) has a density of 3690 kg/m. Alumina particles have an internal porosity of 0.30 and a bulk voidage of 0.41. Estimate the particle density and the bulk density. Which of the four Geldart powder groups (when fluidized by air at atmospheric temperature and pressure) would you expect the alumina powder to be in if the Sauter mean diameter is 100 um