Soda- #9, #59

Carbonic Acid- #9

H2CO3, commonly known as carbonic acid, is a compound with three elements. Carbonic acid is what makes the soda fizzy. 

Source:

http://www.wisegeek.com/what-is-carbonic-acid.htm

Caffeine- #59

Caffeine is a common alkaloid and an ingredient in most sodas.

Source:

http://www.chemistryexplained.com/Bo-Ce/Caffeine.html