Geography · Fluvial Landforms (River Action)
The concept being tested: Andes Mountains - geographic distribution across South American countries.
Consider the following countries: I. Bolivia II. Brazil III. Colombia IV. Ecuador V. Paraguay VI. Venezuela Andes mountains pass through how many of the above countries?
The Andes range runs along the western and northern edge of South America, passing through seven countries in all: Venezuela, Colombia, Ecuador, Peru, Bolivia, Chile and Argentina. Of the six countries listed in this question, four fall on that chain: Bolivia, Colombia, Ecuador and Venezuela. Brazil is excluded because it lies entirely east of the Andes, its terrain shaped instead by the Amazon Basin and the Brazilian Highlands, so the range never enters Brazilian territory. Paraguay is also excluded because it is a landlocked country occupying the Gran Chaco and the Parana Plateau, well to the east of the Andean arc. With Brazil and Paraguay ruled out and the remaining four countries confirmed as genuinely Andean, the correct count is only four.
What UPSC was testing
The question tests whether aspirants can name the actual footprint of the Andes rather than assume it runs through most of South America. The trap is Brazil and Paraguay, both plausible-sounding neighbours of Andean states that the range in fact never reaches.
How often this comes up
This concept has appeared 6 times in UPSC Prelims General Studies Paper I between 2015 and 2025 — in 2021, 2022, 2024 and 2025.
The option-by-option autopsy for this question — why each of the other three is wrong, and which neighbouring concept each one was built from — is in the app.
Other past-year questions touching Fluvial Landforms (River Action).