Which from following pairs of compound is an example of position isomerism?

Which from following pairs of compound is an example of position isomerism?
  1. 2 methylprop-1-ene and But-1-ene
  2. But-2-ene and Cis-But-2-ene
  3. But-2-ene and 2-methylprop-1-ene
  4. But-1-ene and But-2-ene

Solution

$\mathrm{CH}_3-\underset{\text { 1-butene }}{\mathrm{CH}_3}-\mathrm{CH}=\mathrm{CH}_2 \mathrm{CH}_3-\underset{2 \text {-butene }}{\mathrm{CH}}=\mathrm{CH}-\mathrm{CH}_3$ Locant number will differ along same parent C-chain so it is position isomer.

Asked in: MHT CET 2022 (05 Aug Shift 2)

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