What is the hardening agent commonly found in hardening compounds used in embalming?

The correct answer is Plaster of Paris, which is a common hardening agent used in embalming compounds. Plaster of Paris is made from gypsum, which, when mixed with water, can form a solid mass that hardens over time. This property makes it particularly useful in funeral service applications where maintaining the shape and appearance of the deceased is important.

When used in embalming, Plaster of Paris can help fill voids and support tissues that may collapse after the body has been embalmed. Its quick-setting nature allows for immediate results, providing a hardened, supportive structure. This is crucial for preserving the aesthetic integrity during viewing and memorial services.

In contrast, the other options like calcium carbonate and sodium bicarbonate do not possess the same hardening properties when mixed with water. Calcium carbonate is primarily used as a buffering agent, and sodium bicarbonate serves as an alkaline compound but does not harden in the manner necessary for embalming applications. Silica gel is used primarily for desiccating materials and moisture control but also does not function as a hardening agent in embalming compounds. Thus, the unique properties of Plaster of Paris make it the suitable choice in this context.