Question

The sticky fluid which on exposure to air forms a thread of silk

Answer 1

Answer:

Cocoon

Explanation:

Answer 2

Fibroin is the sticky fluid which on exposure to air forms a thread of silk.

-  The salivary gland of silkworm starts secreting a sticky fluid which is a protein called fibroin.

- This sticky fluid gets hardened on exposure to air and forms a long thread of silk.

- Cocoon is formed by this thread of silk wrapped around the silkworm.