Which agent acts as an anti-polymerization agent for HCOH?

The correct answer is methanol. Methanol acts as an anti-polymerization agent for formaldehyde (HCOH) due to its ability to effectively stabilize the reactive species involved in the polymerization process. When formaldehyde is in the presence of methanol, it can form a stable methylene glycol product. This presence of methanol helps prevent the formaldehyde from undergoing further reaction that leads to undesirable polymer chain formation, effectively inhibiting polymerization.

By utilizing methanol, the risk of forming larger, potentially less useful polymers is reduced, enabling controlled reactions and maintaining the desired properties of the formaldehyde solution. The role of methanol is critical, especially in industrial applications where formaldehyde is used. The other agents, such as acetone, ethanol, and isopropanol, do not provide the same level of stabilization against polymerization as methanol does, which is why they are not the correct choice in this context.