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GATE 2019 CY – Question 39

Inorganic Chemistry · Instrumental Methods of Analysis: UV-visible, fluorescence and FT-IR spectrophotometry, NMR and ESR spectroscopy, mass spectrometry, atomic absorption spectroscopy, Mössbauer spectroscopy (Fe and Sn) and X- ray crystallography. Electroanalytical methods – cyclic voltammetry, ion-selective electrodes. Thermo-analytical methods: TGA, DTA and DSC. · 2 marks · Multiple choice

For a methyl radical’s EPR spectrum, what are the number of lines and their relative intensities?

  1. 1 line; 1
  2. 3 lines; 1:2:1
  3. 4 lines; 1:2:2:1
  4. 4 lines; 1:3:3:1

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Show answer and explanation

Correct answer: (D) 4 lines; 1:3:3:1

Explanation

The unpaired electron couples to three equivalent protons, each with spin 1/2. Hyperfine splitting gives 2nI+1=4 lines. The numbers of nuclear-spin arrangements follow the binomial coefficients of (1+x)³: 1:3:3:1. Thus D.

More Instrumental Methods of Analysis: UV-visible, fluorescence and FT-IR spectrophotometry, NMR and ESR spectroscopy, mass spectrometry, atomic absorption spectroscopy, Mössbauer spectroscopy (Fe and Sn) and X- ray crystallography. Electroanalytical methods – cyclic voltammetry, ion-selective electrodes. Thermo-analytical methods: TGA, DTA and DSC. questions

All Instrumental Methods of Analysis: UV-visible, fluorescence and FT-IR spectrophotometry, NMR and ESR spectroscopy, mass spectrometry, atomic absorption spectroscopy, Mössbauer spectroscopy (Fe and Sn) and X- ray crystallography. Electroanalytical methods – cyclic voltammetry, ion-selective electrodes. Thermo-analytical methods: TGA, DTA and DSC. questions →