Formaldehyde is abbreviated as which chemical symbol and is described as a colorless, strong-smelling gas used as a preservative when in solution?

• A. HCOH; colorless, mild-smelling gas used as a solvent
• B. Formic aldehyde
• C. HCHO; colorless, strong-smelling gas that is a powerful preservative when used in solution
• D. Acetaldehyde

Answer: (C)

Formaldehyde’s symbol is HCHO, often written from its formula CH2O. It is a colorless gas with a sharp, strong odor, and when dissolved in water it forms a preservative solution known as formalin. This preservative use is due to formaldehyde’s ability to inactivate microbes and fix tissues. The option that identifies the symbol as HCHO and describes it as a colorless, strong-smelling gas that is a powerful preservative when used in solution matches these real properties. The other options give an incorrect symbol, an informal name, or describe a different compound (acetaldehyde) with different characteristics.