Which substance can be decomposed by a chemical change? 1. sodium 2.argon 3.sulfur 4.amonia

The answer to this question would be: ammonia
Chemical decomposition is the breakdown of a compound into smaller compound or element. In this question, the Sodium(Na), Argon (Ar) and Sulfur(S) is elements, not compounds.
An element should not breakable since it was the simplest form.
Ammonia(NH3) is a compound so it should be able to be decomposed.

Okay this will take 1 hour okay dont forget me.

Exothermic,  physical change after it is already baked