UPPSC 2023 Prelims GS Paper-I · Question 114 of 150

Correct — B, both (A) and (R) are true and (R) is the correct explanation of (A). The Tamil Nadu (Coromandel) coast does stay largely dry during the June-September south-west monsoon (Assertion true). The reason is precisely why: the Bay of Bengal branch of the SW monsoon runs almost parallel to the Coromandel coast as it curves north toward the Ganga plains, so it gives little orographic rain there; and for the Arabian Sea branch, the Tamil Nadu plains lie on the leeward, rain-shadow side of the Western Ghats. With both branches failing to deliver rain, the coast stays dry in the SW monsoon and instead gets most of its rain from the retreating (north-east) monsoon in October-December. Since the reason correctly explains the assertion, the answer is (b).

• (a)(A) is true but (R) is false — The assertion is true, but so is the reason — both the 'parallel to the Bay of Bengal branch' and the 'rain shadow of the Arabian Sea branch' points are correct, so (R) is not false.
• (c)Both (A) and (R) is true but (R) is not correct explanation of (A) — (R) is not merely true alongside (A) — it states the actual cause of the dryness (parallel winds plus Western Ghats rain shadow), so it IS the correct explanation.
• (d)(A) is false but (R) is true — The assertion is not false — the Tamil Nadu coast genuinely receives very little rain during the south-west monsoon season.

The south-west (summer) monsoon splits into two branches — the Arabian Sea branch and the Bay of Bengal branch. The Arabian Sea branch strikes the Western Ghats and drops heavy rain on the west coast, leaving the leeward east (including the Tamil Nadu plains) in a rain shadow. The Bay of Bengal branch is deflected north-westward up the Ganga plains and runs almost parallel to the Tamil Nadu (Coromandel) coast, so it too gives little rain there. Tamil Nadu therefore gets most of its annual rainfall from the retreating/north-east monsoon (October-December).

This is a standard NCERT explanation dressed up as an Assertion-Reason. Check each half: (A) the TN coast is dry in the SW monsoon — true; (R) two mechanisms (winds parallel to the Bay branch + Western Ghats rain shadow for the Arabian branch) — both true, and together they cause the dryness. So the strongest option applies: both true and (R) explains (A).

• The SW monsoon has two branches: the Arabian Sea branch and the Bay of Bengal branch.
• The Tamil Nadu plains lie in the rain shadow (leeward side) of the Western Ghats for the Arabian Sea branch.
• The Bay of Bengal branch runs almost parallel to the Coromandel coast, giving it little SW-monsoon rain.
• Tamil Nadu receives most of its rainfall from the retreating north-east monsoon (October-December).

• Marking '(R) is not the correct explanation' when (R) is in fact the precise cause
• Thinking Tamil Nadu is dry all year — it actually gets heavy north-east-monsoon rain in October-December

Asked as Assertion-Reason or statement items on why the Coromandel coast is dry in the summer monsoon yet wet in the retreating monsoon, and on the two monsoon branches / the rain-shadow effect.

• practice — not a real PYQ

  Tamil Nadu receives most of its annual rainfall during which season?

  • (a)June-September (SW monsoon)
  • (b)October-December (retreating / NE monsoon)
  • (c)March-May (pre-monsoon)
  • (d)January-February (winter)

  Answer(b) October-December — from the retreating / north-east monsoon.

• practice — not a real PYQ

  With respect to the Arabian Sea branch of the monsoon, the Coromandel coast lies in the rain shadow of which mountain range?

  • (a)Eastern Ghats
  • (b)Western Ghats
  • (c)Satpura Range
  • (d)Aravalli Range

  Answer(b) Western Ghats — the leeward, rain-shadow side faces the Tamil Nadu plains.