What happens when excess of phenol is treated with formaldehyde in the presence of acid or alkali?  

Bakelite is formed

The correct answer is option 1. Bakelite is formed.

When phenol is treated with formaldehyde in the presence of an acid or an alkali, a polymerization reaction occurs, leading to the formation of a phenol-formaldehyde resin. Depending on the conditions, this can result in the formation of various products, including linear or cross-linked polymers.

Thus, when an excess of phenol is treated with formaldehyde in the presence of an acid or alkali, the product formed is: Bakelite is formed

This thermosetting plastic is highly cross-linked, durable, and resistant to heat and chemicals, making it one of the earliest synthetic polymers used in industrial applications.