Which chemical is present in chitinous exoskeleton?

Explanation

**Step-by-Step Solution:**

1. **Identify the Structure**: The question asks about the chemical present in the chitinous exoskeleton. The term "chitinous" indicates that we are looking for a specific chemical compound associated with exoskeletons.

2. **Recognize the Chemical**: The primary chemical that forms the chitinous exoskeleton is chitin. It is important to note that chitin is a key component in the structure of the exoskeletons of various organisms.

3. **Understand the Characteristics of Chitin**: Chitin is described as a semi-transparent and tough substance. This characteristic is crucial as it provides strength and protection to the organisms that possess it, such as arthropods (e.g., crustaceans and insects).

...