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GATE 2025 CY – Question 24

Organic Chemistry · Experimental Techniques in Organic Chemistry: Optical rotation (polarimetry). Application of various chromatographic techniques such as thin-layer, column, HPLC and GC. Applications of UV-visible, IR, NMR spectroscopy and Mass spectrometry in the structural determination of organic molecules. · 1 mark · Multiple select

Compound(s) that show(s) an intense peak at m/z 120 in the EI mass spectrum is/are

Four aromatic carbonyl compounds for EI mass-spectral fragmentation.
  1. Option A in the figure
  2. Option B in the figure
  3. Option C in the figure
  4. Option D in the figure

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Show answer and explanation

Correct answer: (A) Option A in the figure; (B) Option B in the figure; (D) Option D in the figure

Explanation

The accepted compounds are A, B and D. Compare the fragment connectivity and allowed hydrogen transfers in each drawn structure with an ion of m/z 120. The previous assignment A,C,D incorrectly excluded B and included C; its proposed fragmentation routes should not be used to justify that combination.

Official GATE 2025 answer key: https://gate2026.iitg.ac.in/doc/download/2025_Key/CY_Keys.pdf