**4. Physical characterization of molecule**

Most often than not, new chemical entity exists in solid form and the properties under study during preformulation phase are bulk property characterization and micromeritic property characterization. Bulk property characterization includes study of polymorphism, crystallinity, density, nature of molecule like deliquescence or hygroscopicity and micromeritic characterization includes study of particle size, shape, porosity, and density. As most of the new chemical entities are solids, they exist either as amorphous or in crystalline state. Either of the form imparts the two main virtues that are stability and solubility.
