MPSC 2022 Prelims Paper-I · Question 4 of 100

Correct — option (1). Column I holds four hypotheses about the origin of the solar system and Column II holds four names; the columns are printed alongside each other, but that is layout and asserts no pairing, so each theory has to be attached to its author from what is known of it. Take the one that is certain first. The Nebular Theory at (c) is Laplace's: Pierre-Simon Laplace set it out in 1796, proposing that a hot, rotating gaseous nebula contracted as it cooled, spun faster, and shed successive rings of matter at its equator which condensed into the planets while the residue formed the sun. So (c) goes with (i), and that single pairing decides the question, because option (1) is the only row that makes it. The other three pairings confirm the row rather than establish it. The Cepheid Theory at (a) is the work of A. C. Banerji, printed here as Dr. Banerji, who proposed in the early 1940s that the sun was originally a Cepheid, one of the class of pulsating stars, and that the approach of another star intensified its pulsation until matter was thrown off and condensed into the planets; so (a) goes with (ii). The Electromagnetic Theory at (b) is Hannes Alfven's, which brought the sun's magnetic field into the account and had ionised gas from a surrounding cloud sorted by that field according to the mass of its atoms before the planets formed; so (b) goes with (iii). The Binary Theory at (d) is R. A. Lyttleton's, in which the sun once had a companion star and a third, intruding star tore the companion apart, the debris being left in orbit around the sun; so (d) goes with (iv). The completed pairing is (a)-(ii), (b)-(iii), (c)-(i), (d)-(iv), which is option (1).

• (2)(a) - (iii), (b) - (iv), (c) - (ii), (d) - (i) — This row gives the Nebular Theory at (c) to Dr. Banerji, and that alone disposes of it. The nebular hypothesis is the oldest of the four and the best known: Kant proposed a version of it in 1755 and Laplace gave it its classic form in 1796, and it is the one theory in this list that every candidate is expected to be able to place. The row compounds the error by giving the Cepheid Theory to Alfven, whose contribution was electromagnetic, and the Electromagnetic Theory to Lyttleton, whose contribution was the binary star. Nothing in it survives. The point worth taking away is procedural: in a four-by-four match it is enough to hold one pairing with certainty, because a single confirmed pair usually eliminates three of the four rows without any need to test the remaining pairs.
• (3)(a) - (iv), (b) - (ii), (c) - (iii), (d) - (i) — This row gives the Nebular Theory at (c) to Alfven, which is wrong for the same reason as the previous row — the nebular hypothesis belongs to Laplace, whose 1796 account of a cooling, contracting and rotating nebula shedding rings is the version taught everywhere. Alfven's place in this list is the Electromagnetic Theory, which is a genuinely different idea: it makes the sun's magnetic field the agent that separates and arranges the ionised material out of which the planets form, and it belongs to the twentieth century rather than the eighteenth. The row also gives the Cepheid Theory to Lyttleton and the Binary Theory to Laplace, so it inverts almost every pairing in the question. A candidate who has fixed even the Laplace pairing will not reach it.
• (4)(a) - (i), (b) - (iv), (c) - (ii), (d) - (iii) — This is the row most likely to catch a hurried reader, because it opens with a name everyone recognises: it gives the Cepheid Theory at (a) to Laplace, and Laplace is the one name in the second column that a candidate is sure to know. That familiarity is what the row trades on. Laplace belongs to the Nebular Theory at (c), and this row gives that to Dr. Banerji instead, while handing the Electromagnetic Theory to Lyttleton and the Binary Theory to Alfven. Every pair is wrong. The discipline that defeats it is to decide where your one secure name belongs before reading any row, and then to accept only a row that puts it there; reading the rows first lets a familiar name in the wrong slot pass for a familiar name in the right one.

Theories of the origin of the solar system divide into two families, and holding the division is worth more than memorising any single theory. The monistic or evolutionary family derives both the sun and the planets from a single parent body: Kant's and Laplace's nebular hypothesis is the classic case, and the modern solar nebula model, in which a rotating disc of gas and dust around the young sun accretes into planetesimals and then planets, is its descendant. The dualistic or catastrophic family requires a second body, usually a passing or companion star, to pull material out of the sun or out of its companion: Chamberlin and Moulton's planetesimal hypothesis, the tidal hypothesis of Jeans and Jeffreys, the binary star hypothesis of Russell and Lyttleton, the supernova hypothesis of Hoyle and Lyttleton, and Banerji's Cepheid hypothesis all belong here. Alfven's electromagnetic hypothesis stands somewhat apart, since its distinctive claim concerns the mechanism of sorting rather than the source of the material: the sun's magnetic field acts on ionised gas, and atoms of different mass are captured at different distances. The catastrophic theories fell out of favour largely because a close stellar encounter is far too rare an event to account for the number of planetary systems now known, and because material torn from a star would be too hot to condense; the nebular idea, in its modern form, is what survives.

Attribution questions are cheap for a commission to set and quick to mark, and MPSC uses them heavily in the physical geography block. The four names printed here are of very unequal familiarity — Laplace is known to everyone, Alfven and Lyttleton to a candidate who has read the chapter, and Dr. Banerji only to one who has read it closely — and the question is built so that the most familiar name is the lever. Every wrong row in this item detaches the Nebular Theory from Laplace, so a candidate who knows nothing else can still answer it correctly, which is a general property of matching items worth exploiting: find the pair you cannot be wrong about, and eliminate on it. The second habit the question rewards is not being unsettled by an unfamiliar name. Dr. Banerji is A. C. Banerji, whose Cepheid theory of the origin of the solar system was published in the early 1940s, and an Indian name in a list of European ones is a normal feature of the Indian geography syllabus rather than a sign that the option has been invented.

• The nebular hypothesis is Laplace's, set out in 1796: a hot rotating gaseous nebula contracts as it cools, spins faster and sheds equatorial rings that condense into planets, the residue forming the sun. Kant had proposed an earlier version in 1755.
• The Cepheid hypothesis is A. C. Banerji's, published in the early 1940s: the sun was a Cepheid variable whose pulsation was intensified by an approaching star until matter was ejected and condensed into planets.
• The electromagnetic hypothesis is Hannes Alfven's: the sun's magnetic field acts on ionised gas from a surrounding cloud, capturing atoms of different mass at different distances, and the planets form from that sorted material.
• The binary star hypothesis is R. A. Lyttleton's: the sun once had a companion star which a third intruding star destroyed, the debris remaining in orbit around the sun to form the planets.
• Theories of origin fall into two families — monistic or evolutionary, deriving sun and planets from one body, and dualistic or catastrophic, requiring a second star — with the modern solar nebula model belonging to the first.

• Choosing a row because a familiar name appears in it, without first deciding which theory that name belongs to
• Treating an unfamiliar name in an option as evidence that the option is invented, when Indian contributions are a normal part of this syllabus
• Confusing the electromagnetic hypothesis with the binary star hypothesis, which is the swap two of the wrong rows here depend on
• Reading the side-by-side columns as though the printing paired them, when the layout of a matching question asserts nothing at all

The origin of the earth and the solar system is examined in MPSC papers as a name-to-theory match of exactly this kind, as a single-line attribution question asking who propounded a named hypothesis, and occasionally as a statement question about what a particular theory claims. The names that recur are Kant, Laplace, Chamberlin and Moulton, Jeans and Jeffreys, Russell, Lyttleton, Hoyle, Alfven, Otto Schmidt, Von Weizsacker and Kuiper, together with A. C. Banerji for the Cepheid theory. Because the list is short and fixed, a table of theory against author, with one line on what each theory actually says and which family it belongs to, answers every version of the question. The variant that catches candidates who have learnt only the names is the one that describes a mechanism and asks which theory it belongs to.

No directly related past PYQ was found.

• practice — not a real PYQ

  The hypothesis that the sun's magnetic field acted on ionised gas so that atoms of different mass were captured at different distances, forming the planets, is associated with which scientist ?

  • (a)Hannes Alfven
  • (b)R. A. Lyttleton
  • (c)Pierre-Simon Laplace
  • (d)Otto Schmidt

  Answer(a) Hannes Alfven — his electromagnetic hypothesis makes the sun's magnetic field the sorting agent, which is what distinguishes it from the catastrophic theories that rely on a second star. Lyttleton's binary star hypothesis needs a companion and an intruder, Laplace's nebular hypothesis derives everything from a single rotating nebula, and Otto Schmidt's account works from an interstellar cloud of dust.

• practice — not a real PYQ

  Which of the following theories of the origin of the solar system is monistic, that is, it derives both the sun and the planets from a single parent body ?

  • (a)The tidal hypothesis of Jeans and Jeffreys
  • (b)The binary star hypothesis of Lyttleton
  • (c)The nebular hypothesis of Laplace
  • (d)The Cepheid hypothesis of Banerji

  Answer(c) The nebular hypothesis of Laplace — a single hot rotating nebula contracts, sheds rings and forms both the sun and the planets, with no second body required. The other three are dualistic or catastrophic: each needs an intruding or companion star to draw the planetary material out, which is the feature that made them vulnerable once it was realised how rare such encounters would have to be.