UPSC Prelims 2025 Q23: Geography – Astronomy & Earth - Sun System
Consider the following water bodies:
I. Lake Tanganyika
II. Lake Tonlé Sap
III. Patos Lagoon Through how many of them does the equator pass?
- (a) Only one
- (b) Only two
- (c) All the three
- (d) None
Answer: (d) None
Explanation
Water Bodies and the Equator:
| Water Body | Location | Latitude | Equator Passes Through? |
|---|---|---|---|
| Lake Tanganyika | East Africa | ~3°S-9°S | NO - equator passes slightly north of Tanganyika |
| Lake Tonlé Sap | Cambodia, SE Asia | ~13°N | NO - 13 degrees north of equator |
| Patos Lagoon | Southern Brazil | ~31°S | NO - 31 degrees south of equator |
The equator passes through NONE of these three.
Critical distinction: The equator passes through Lake Victoria (East Africa) — NOT Lake Tanganyika.
These are two different lakes that students often confuse.
Answer: (d) None.
Why each option is right or wrong
- (a) Incorrect. The equator does not pass through Lake Tanganyika — it passes through Lake Victoria (a different East African lake). Tanganyika is south of the equator.
- (b) Incorrect. Two is wrong — none of these water bodies have the equator passing through them.
- (c) Incorrect. All three cannot be correct — none of them are on the equator.
- (d) CORRECT. The equator passes through none of the three. Tanganyika (~3-9°S), Tonlé Sap (13°N), and Patos Lagoon (31°S) are all clearly off the equator.
Key point
Equator passes through NONE of these three. Victoria (YES) vs Tanganyika (NO) — the classic East Africa confusion. Tonlé Sap = Cambodia, 13°N. Patos = Brazil, 31°S.
Remember
Equator passes through NONE of these three water bodies — a classic geography trick question.
Common mistakes
- Confusing Lake Victoria (equator passes through it) with Lake Tanganyika (equator does not). They are different East African lakes — Victoria is north, Tanganyika is further south.
- Assuming Cambodia is equatorial. Tonlé Sap is at 13°N — tropical, but not on the equator.
- Not knowing Patos Lagoon is in southern Brazil near Uruguay (~31°S) — subtropical, not anywhere near the equator.
Exam tip
East Africa lakes + equator: Victoria (YES), Tanganyika (NO), Malawi/Nyasa (NO). This is the most commonly confused pair in UPSC geography. Victoria = equatorial. Tanganyika = south.
Sources
- NCERT Class 11 Geography - Fundamentals of Physical Geography
- World Geography - Latitude and Water Bodies