MPSC 2026 Prelims Paper-I · Question 21 of 100

Correct — option (4), '(a), (b), (c), (d)'. Every one of the four named items exists for the same reason, so all four belong to the same family of corrections. The reason is that the three natural clocks humans reckon time by are not whole multiples of one another: the civil day is 24 hours, the synodic month (new moon to new moon) is about 29.53 days, and the tropical year is about 365.2422 days. No calendar can hold all three in step on its own, so every calendar carries a correction that periodically adds or drops a unit. Statement (a), the leap year, is the day-level correction: because the tropical year runs about a quarter of a day past 365, a day is added every fourth year, and because that over-corrects slightly, century years are not leap years unless divisible by 400. Statement (b), Adhik Mass, is the month-level correction in the Indian luni-solar calendar: twelve lunar months make about 354 days, roughly 11 days short of the solar year, so an extra thirteenth month is intercalated about every 32 to 33 months — the working rule being that a lunar month in which no sankranti (the Sun's entry into a new rashi) falls is declared adhika. Statement (c), Kshay Mass, is the same correction running the other way: a lunar month that contains two sankrantis is dropped altogether. Statement (d), Tithi Vridhhi-lope, is the day-level correction inside the lunar reckoning: a tithi is one-thirtieth of a lunation, defined as each 12 degrees by which the Moon pulls ahead of the Sun, and because both bodies move at varying apparent speeds a tithi runs anywhere from roughly 19 to about 26 hours. A tithi that begins and ends between two sunrises touches no sunrise and is omitted (lopa or kshaya); one that spans two sunrises is repeated (vriddhi). Insertion, deletion, repetition, omission — four devices, one purpose. Option (4) is the only choice that contains all four, and it is right here not because it is the longest option but because each named item can be shown, independently, to belong.

• (1)(b) and (c) — Keeps only the two month-level devices, Adhik Mass and Kshay Mass, and throws out both day-level ones. That is an arbitrary cut: the leap day and the tithi vriddhi-lopa rule do exactly the same job at a finer grain — they absorb the fractional remainder that the larger unit cannot hold. A candidate lands here by reading the question as being about the Hindu lunar month specifically, when the stem asks about the process of time measurement in general and lists a Gregorian device, (a), in the same breath as three panchang devices.
• (2)(c) and (d) — Keeps Kshay Mass and Tithi Vridhhi-lope but drops Adhik Mass, which is the single most familiar and most frequently applied of the four — it recurs about every third year, whereas a kshaya masa is rare. Any pairing that admits the deletion of a month while excluding the insertion of one is internally inconsistent, because both follow from the same sankranti test applied to a lunar month: no sankranti means adhika, two sankrantis mean kshaya.
• (3)Only (a) — The narrowest reading — that only the Gregorian leap year counts as a time-drift correction. It fails on the plain content of the other three: adhika masa, kshaya masa and tithi vriddhi-lopa are all documented adjustments in Indian calendrical practice, printed every year in every panchang, and each one exists precisely to reconcile a reckoning unit with the astronomical period it is meant to track. Choosing (3) requires treating 'time measurement' as a purely Western calendrical exercise, which the stem's own list contradicts.

A calendar is an attempt to build whole numbers out of periods that are not whole. The day is set by the Earth's rotation, the month by the Moon's revolution around the Earth, and the year by the Earth's revolution around the Sun; none divides evenly into another. Three answers exist. A purely solar calendar (Gregorian) tracks the year and lets the month drift free of the Moon, paying for the year's fractional quarter-day with a leap day. A purely lunar calendar (Hijri) tracks the Moon and lets its year of about 354 days slide backwards through the seasons. A luni-solar calendar — which is what the Indian panchang is — refuses to give up either, and therefore needs the heaviest machinery: an intercalary month (adhika masa) to make up the roughly eleven-day annual shortfall, a suppressed month (kshaya masa) when the correction overshoots, and a rule for tithis that do not line up with sunrise, giving repeated tithis (vriddhi) and omitted ones (lopa or kshaya). The four items in this question are simply the four rungs of that one ladder.

Maharashtra's panchang tradition is a live one — festival dates, the Shalivahana Shaka new year at Gudi Padwa, and the placement of Adhik Maas are worked out every year and published, so this is general awareness with a local edge rather than astronomy. The examiner is not asking a candidate to compute anything; the stem lists four devices and asks whether each is part of the correction apparatus. That makes the all-inclusive option the natural target, and the reasoning a candidate must supply is item-by-item: an inclusive option is defensible only when every named item can be justified on its own, and is destroyed the moment one of them can be shown not to belong. Here none of the four can be dislodged. Note also that the English phrase printed in the stem, 'Time Lapse Analysis', is a rendering of the Marathi 'कालांतर संस्कार' and is not a standard technical term in English-language astronomy — read the Marathi column for the sense the setter intended.

• Tropical year is about 365.2422 days. The Gregorian rule adds one day every four years and then withdraws it in century years not divisible by 400 — so 1900 was not a leap year and 2000 was, and the calendar stays within about one day of the Sun over three thousand years.
• Synodic month (new moon to new moon) averages about 29.53 days, so twelve lunar months come to roughly 354 days — about eleven days short of a solar year. Left uncorrected, the lunar year would slide a full season out of place within about eight years.
• Adhika masa (Adhik Mass) is the intercalary thirteenth month inserted about once in 32 to 33 months. The operative test is astronomical, not arithmetical: a lunar month in which no sankranti falls — that is, in which the Sun does not cross into a new rashi — is declared adhika.
• Kshaya masa (Kshay Mass) is the reverse case, a lunar month containing two sankrantis, which is therefore dropped. It is rare, and can only occur when the Sun's apparent motion is at its fastest, which confines it to the winter months of the Indian calendar.
• A tithi is one-thirtieth of a lunation, defined by each 12 degrees of the Moon's elongation from the Sun. Because both apparent motions vary, a tithi lasts roughly 19 to 26 hours. A tithi enclosed entirely between two sunrises is omitted (lopa/kshaya); one that spans two sunrises is repeated (vriddhi).
• India's national calendar uses the Saka era and was brought into official use on 22 March 1957, on the recommendation of the Calendar Reform Committee chaired by the physicist Meghnad Saha.

• Reading 'leap year' as a purely Western device and excluding it from a question about kaal-ganana. The stem lists it alongside three panchang terms precisely to test whether a candidate sees the shared purpose rather than the differing vocabulary.
• Swapping adhika masa and kshaya masa. One is an inserted month, the other a suppressed month; both come from the same sankranti test, which is why a candidate who remembers the test never confuses them and a candidate who memorised only the names often does.
• Treating a tithi as though it were a civil day of fixed length. It is an angular measure — 12 degrees of the Moon's elongation from the Sun — and its variable duration is the whole reason vriddhi and lopa exist at all.

Calendar questions reach the Commission's paper in three recognisable shapes. First, definition-matching: a term such as Adhik Maas, Kshaya Maas, tithi or sankranti is set against its meaning in a two-column match. Second, the inclusive-list shape used here, where several devices are listed and the candidate must decide whether each belongs to a common category — these are solved item by item, never by pattern. Third, the institutional fact: who chaired the Calendar Reform Committee, which era the national calendar uses, and from what date it was adopted. A candidate who holds the sankranti rule, the roughly eleven-day lunar shortfall and the 22 March 1957 adoption date can answer all three shapes without any computation.

No directly related past PYQ was found.

• practice — not a real PYQ

  In the Indian luni-solar calendar, a lunar month is declared 'Adhika Masa' (intercalary month) when, during that month —

  • (a)two sankrantis occur
  • (b)no sankranti occurs
  • (c)two full moons occur
  • (d)the Sun reaches its perihelion

  Answer(b) no sankranti occurs — the Sun fails to cross into a new rashi during that lunar month, so an extra month is inserted to make up the roughly eleven-day gap between twelve lunar months and the solar year. The mirror case, a lunar month containing two sankrantis, is the rare Kshaya Masa, which is dropped instead of inserted.

• practice — not a real PYQ

  India's national calendar, which uses the Saka era and was recommended by the Calendar Reform Committee headed by Meghnad Saha, came into official use from :

  • (a)15 August 1947
  • (b)26 January 1950
  • (c)22 March 1957
  • (d)1 January 1960

  Answer(c) 22 March 1957 — the date on which the Saka-era national calendar was brought into official use, following the Calendar Reform Committee set up in 1952 under the physicist Meghnad Saha. The dates in the other three options belong to Independence, the commencement of the Constitution and no calendar event at all.