Formaldehyde in a dry powdered form is also known as what?

Formaldehyde in a dry powdered form is known as paraformaldehyde. Paraformaldehyde is a polymerized version of formaldehyde, typically taking the form of a white powder. It can be produced by the heating or evaporation of formaldehyde solutions, resulting in a compound that is less volatile and more stable in powdered form. This makes it suitable for various applications, particularly in histology and microscopy, where it is used as a fixative.

The other choices refer to different substances. Formalin is an aqueous solution of formaldehyde and is commonly used as a preservative or disinfectant. Methenamine, on the other hand, is a compound that can be derived from formaldehyde but is distinct in its chemical composition and uses. Acetaldehyde is a different aldehyde altogether and is not a form of formaldehyde. Understanding these distinctions helps clarify why paraformaldehyde is correctly identified as the dry powdered form of formaldehyde.