A chemical NOT used as a perservative for treating wood fencing is:

• A. Pentachlorophenol
• B. Creosote
• C. Calcium Chloride
• D. Ammonal Copper Zinc Arsenate

Answer: (C)

Wood preservation hinges on chemicals that penetrate wood and stay there to resist decay and insect attack. Pentachlorophenol, creosote, and ammonical copper zinc arsenate are classic preservatives chosen to protect lumber for years by bonding with the wood fibers. Calcium chloride, by contrast, is a hygroscopic salt used mainly for moisture control and de-icing; it doesn’t provide long-term protection inside wood and tends to move out of the wood over time. For treating wood fencing, calcium chloride isn’t used as a preservative, making it the correct answer in this context.