What does formaldehyde become when it polymerizes?

When formaldehyde polymerizes, it transforms into paraformaldehyde. This process occurs when formaldehyde molecules link together to form a polymeric structure. Paraformaldehyde is a white, solid substance that is commonly used in various applications, including as a formaldehyde source in laboratories and as a preservative in biological specimens.

The appeal of paraformaldehyde lies in its stability as a solid compared to the gaseous form of formaldehyde, making it easier to handle in many situations where controlled doses of formaldehyde are needed.

In contrast, the other choices do not represent the polymerized form of formaldehyde. Polyethylene, for example, is not related as it is a polymer derived from ethylene, while formic acid and carbaldehyde do not involve the polymerization of formaldehyde. Understanding the transformation of formaldehyde into paraformaldehyde is crucial, particularly in fields like mortuary science, where the use of formaldehyde for embalming is prevalent.