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GS Paper IUPSC Prelims 1997
Indian Geography
Question No. 323Interactive Test Mode
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+2-0.66

Q323. The January isotherm taken as a basis for dividing India into tropical and subtropical zones is:

The January isotherm taken as a basis for dividing India into tropical and subtropical zones is:

Select the correct option below (or cross out options to eliminate)
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Official Answer Key & Detailed Solution

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Official UPSC Answer KeyUPSC Prelims 1997 • Geography

Correct Answer: Option (B) — 18°C

Concept & Option Breakdown

Standard Reference Verified

The 18°C mean January isotherm runs roughly parallel to the Tropic of Cancer across central India and is standardly used by climatologists (such as in Koeppen's scheme) to demarcate the tropical zone (south of the isotherm, where mean monthly winter temperatures stay ≥ 18°C) from the subtropical zone (north of the isotherm).

Elimination Heuristic & Exam Approach

In Koeppen's climatic classification, 18°C in the coolest month is the fundamental boundary dividing tropical (A) climates from temperate/subtropical (C) climates.

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Question Specifications & Syllabus Mapping

Examination & YearUPSC Civil Services Preliminary Examination 1997 (Q323)
Paper & Marking SchemeGS Paper I • 2 Marks (-0.66 Negative for incorrect response)
Syllabus Subject & TopicGeography → Indian Geography
Official Answer KeyOption (B) — 18°C

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Frequently Asked Questions — UPSC Prelims 1997 Q323

What is the official answer for UPSC Prelims 1997 GS Paper I Question 323 (Geography)?

The official UPSC answer key for this 1997 Geography (Indian Geography) question is Option (B): "18°C". Correct attempts carry 2 Marks with -0.66 Negative penalty for wrong answers.

Which UPSC Prelims syllabus topic does this 1997 question belong to?

This question belongs to GS Paper I under the subject "Geography" and micro-topic "Indian Geography". You can explore all repeated questions from Indian Geography in Acme AI's 3D Prelims PYQ Realm or practice 50 full-length and sectional tests in the APT Prelims Test Series.

How can I solve this Indian Geography UPSC Prelims question using option elimination?

In Koeppen's climatic classification, 18°C in the coolest month is the fundamental boundary dividing tropical (A) climates from temperate/subtropical (C) climates.

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