_______ formed in the shapes of the entrapped mannitol crystals

• A. Microchannels
• B. Macropores
• C. Nanopores
• D. Dense blocks

Answer: (B)

Macropores are formed when a porogen like entrapped mannitol crystals is later removed, leaving voids that mirror the shape and size of the crystals. Mannitol crystals are relatively large, so after dissolution, the resulting pores are sizable and crystal-shaped, fitting the macropore range rather than nanoscopic or microchannel-scale voids. If you were creating nanopores, the voids would be on the nanometer scale; microchannels would appear as elongated pathways rather than discrete crystal-shaped holes; dense blocks would lack porosity. This crystal-templating approach explains why the pore spaces reflect the crystal geometry and are classified as macropores.