MPSC 2024 Prelims Paper-I · Question 28 of 100

Correct — option (1), the Mississippi. The stem is careful to say 'from the options below', and that phrasing matters: of the four rivers offered, the Mississippi is by a wide margin the longest. It rises at Lake Itasca in northern Minnesota and runs roughly 3,766 kilometres south to its delta on the Gulf of Mexico, passing St Louis, Memphis and New Orleans. The next longest option, the Columbia, is little more than half that; the Snake is shorter still, and the Hudson is barely a seventh of the Mississippi's length. So the ranking within this option set is not close and the question turns on knowing the rough scale of each river rather than on any fine measurement. Two further facts make the Mississippi the natural answer to a question about American rivers. Its drainage basin is the third largest in the world after those of the Amazon and the Congo, gathering water from thirty-one states and two Canadian provinces — essentially the whole interior of the United States between the Rockies and the Appalachians. And with its great tributary the Missouri it forms a combined system among the longest on earth. That tributary is worth naming explicitly, because standard measurements make the Missouri itself marginally longer than the Mississippi and it is often listed as the longest single river in the United States; but the Missouri is not among the four options here, so it cannot affect this answer. Within the list the paper actually prints, the Mississippi stands alone at the top, and option (1) is right.

• (2)The Columbia — The Columbia is a major river but a much shorter one, running about 2,000 kilometres from its source in British Columbia through Washington and along the Washington-Oregon boundary to the Pacific. It is the largest river by volume flowing into the Pacific from North America and is heavily dammed for hydroelectricity, which gives it a prominence out of proportion to its length and makes it a plausible-sounding answer. But volume of flow and economic importance are not what the stem asks about, and on length the Columbia is little more than half the Mississippi.
• (3)The Snake — The Snake is about 1,735 kilometres long and is itself a tributary — the largest tributary of the Columbia, which it joins in southeastern Washington after cutting Hells Canyon along the Idaho-Oregon boundary. A river that flows into another river in the same option list is very unlikely to be the longest in the country, and that structural observation alone should push it down the ranking. It is roughly half the length of the Mississippi and cannot be the answer.
• (4)The Hudson — The Hudson is the shortest of the four by a very large margin, at roughly 500 kilometres from the Adirondack Mountains of New York south to New York Harbour. Its fame is historical and commercial rather than physical: it carried the early European settlement of the region, and with the Erie Canal it opened a route from the Atlantic to the Great Lakes. Prominence in American history is exactly what makes it a tempting name to a candidate guessing on recognition, and exactly why the question rewards a rough sense of each river's actual scale.

The drainage of the United States is organised by two mountain systems and the vast interior between them. The Rocky Mountains in the west and the Appalachians in the east enclose the Mississippi basin, which collects the runoff of the central lowland and carries it south to the Gulf of Mexico. The Mississippi itself flows from Lake Itasca in Minnesota to a birdfoot delta below New Orleans, and it gathers three great tributaries on the way — the Missouri from the northern plains, the Ohio from the Appalachian side, and the Arkansas from the south-west. Its basin covers about forty per cent of the conterminous United States and is the third largest drainage basin in the world. West of the Rockies the drainage is quite different: short, steep rivers reach the Pacific over a much shorter distance, the Columbia and its tributary the Snake being the largest of them, and they are valued more for hydroelectric power and irrigation than for navigation. On the Atlantic side the rivers are shorter still, the Hudson among them, because the Appalachian divide lies close to the coast.

World geography questions in MPSC papers usually turn on a single comparative fact — the longest, the largest, the highest, the deepest — and they are answered by holding an approximate magnitude for each candidate rather than an exact figure. This question is a good example of why approximation is enough: the Mississippi is roughly twice the Columbia and roughly seven times the Hudson, so no precise number is needed to rank them. The stem's own wording, 'from the options below', is also worth reading as a signal. It restricts the comparison to the printed list, which matters here because the Missouri, usually measured as marginally the longest single river in the United States, is not offered. When a stem confines a superlative to the given options, the task is to rank the four in front of you, not to recall a global answer that may involve a name the paper never printed.

• The Mississippi rises at Lake Itasca in Minnesota and flows about 3,766 kilometres south to its delta on the Gulf of Mexico.
• The Mississippi's drainage basin is the third largest in the world, after the Amazon and the Congo, and takes in water from thirty-one US states and two Canadian provinces.
• The Missouri, the Mississippi's largest tributary, is by standard measurements marginally longer than the Mississippi itself and is often listed as the longest single river in the United States; it is not among this question's options.
• The Columbia, about 2,000 kilometres long, rises in British Columbia and is the largest river by volume flowing to the Pacific from North America; the Snake is its largest tributary.
• The Hudson, at roughly 500 kilometres, is short but historically important, giving New York its harbour and, through the Erie Canal, a route from the Atlantic to the Great Lakes.

• Answering from fame rather than size — the Hudson is one of the best-known American rivers and one of the shortest offered here
• Overlooking the stem's restriction to the printed options and searching memory for the Missouri, which is usually ranked the longest single US river but is not on this list
• Confusing volume of flow with length; the Columbia carries an enormous discharge to the Pacific but is little more than half the Mississippi in length
• Failing to notice that the Snake is a tributary of another river in the same list, which makes it structurally improbable as the longest

MPSC's world geography questions favour superlatives and comparisons — longest river, largest desert, highest waterfall, deepest lake — because they can be set as one-line questions with four well-known names. The wrong options are usually famous rivers of the same country or continent, so recognition alone does not discriminate; what discriminates is holding a rough order of magnitude for each. Where the stem adds a phrase like 'from the options below', treat it as an instruction to rank only what is printed, since the globally correct answer may deliberately have been left out.

No directly related past PYQ was found.

• practice — not a real PYQ

  The Snake river of the United States is the largest tributary of which river ?

  • (a)The Mississippi
  • (b)The Colorado
  • (c)The Columbia
  • (d)The Rio Grande

  Answer(c) The Columbia — the Snake rises in the Rocky Mountains, cuts Hells Canyon along the Idaho-Oregon boundary and joins the Columbia in southeastern Washington before the combined river reaches the Pacific. The Mississippi's largest tributary is the Missouri; the Colorado and the Rio Grande belong to separate drainage systems in the south-west.

• practice — not a real PYQ

  The Mississippi river drains into which of the following ?

  • (a)The Gulf of Mexico
  • (b)The Atlantic Ocean at Chesapeake Bay
  • (c)The Pacific Ocean
  • (d)Hudson Bay

  Answer(a) The Gulf of Mexico — the Mississippi flows south from Lake Itasca in Minnesota to a birdfoot delta below New Orleans, carrying the runoff of the central lowland between the Rockies and the Appalachians. Its basin covers about forty per cent of the conterminous United States and is the third largest drainage basin in the world.