What countries in South America does the Tropic of Cancer pass through?

The Bahamas and Mexico - but none of these are in South America, rather the Caribbean and Central America.

None.

https://en.wikipedia.org/wiki/Image:World_map_with_tropic_of_cancer.jpg

Could you have meant the Tropic of Capricorn?

The Tropic of Capricorn lies at 23.5° South of the equator and runs through Australia, Chile, southern Brazil (Brazil is the only country that passes through both the equator and a tropic), and northern South Africa.
http://geography.about.com/library/misc/blequator.htm

The Tropic of Capricorn passes through the following countries, starting at the prime meridian and heading west:

* Brazil
* Paraguay
* Argentina
* Chile
* French Polynesia (France) - passing just south of Tubuai
* Tonga - passing just north of the Minerva Reefs
* Australia
* Madagascar
* Mozambique
* South Africa
* Botswana
* Namibia

https://en.wikipedia.org/wiki/Tropic_of_Capricorn