In world geography, which major river of the world crosses the equator two times on its course from source to mouth?

Introduction / Context:
Rivers often serve as important reference points in world geography, and some have unique paths that create interesting exam questions. One such question asks about a river that crosses the equator two times on its journey from its source to its mouth. Knowing this fact helps in understanding the layout of continents and key river systems in Africa and South America.

Given Data / Assumptions:

• We are asked to identify a river that crosses the equator twice.
• Options include the Congo, Amazon, and Nile Rivers, as well as a none of the above option.
• We assume a basic awareness of where these rivers flow on the world map.

Concept / Approach:
The Congo River in central Africa has a distinctive S shaped course that takes it across the equator two times. It flows through the equatorial region, looping north and south as it passes through the Congo Basin before reaching the Atlantic Ocean. By contrast, the Amazon River in South America lies entirely close to the equator but does not cross it twice, and the Nile flows mainly from south to north without this pattern. Therefore, the river that fits the description is the Congo River.

Step-by-Step Solution:
Step 1: Visualise the Congo River on a map of Africa. It flows through the Democratic Republic of the Congo and the Republic of the Congo in the equatorial region. Step 2: Note that the river path loops across the equator in central Africa, crossing it once as it flows northward and again as it turns southward. Step 3: Consider the Amazon River in northern South America. It is close to the equator but does not cross it two times in the same way. Step 4: Consider the Nile River, which flows north through eastern Africa into the Mediterranean Sea and does not cross the equator twice. Step 5: Therefore, the only river among the options that crosses the equator two times is the Congo River.

Verification / Alternative check:
Geography books and maps show the Congo Basin straddling the equator, with the Congo River weaving across this line. The river drains a vast rainforest region and is often described as the second longest river in Africa and the second largest in the world by discharge after the Amazon. Detailed maps clearly depict it crossing the equator twice, which confirms that the Congo River matches the description given in the question.

Why Other Options Are Wrong:

• Amazon River: It flows near the equator in South America but does not cross it twice.
• Nile River: It flows mostly northward in eastern Africa and crosses the equator only once, in its upper reaches.
• None of the above: This is incorrect because the Congo River satisfies the condition.

Common Pitfalls:
A common mistake is to choose the Amazon River just because it is strongly associated with equatorial rainforest and large volume. Another error is assuming the Nile might cross the equator more than once due to its length. To avoid such mistakes, carefully visualise the shapes of the continents and remember the unique S shaped path of the Congo River in central Africa that allows it to cross the equator two times.

Final Answer:
The river that crosses the equator twice is the Congo River.