Final answer:
The M peak in a mass spectrum indicates the molecular ion or parent ion, representing the molecule's molecular weight and aiding in substance identification.Answer is OPTION A.
Step-by-step explanation:
In mass spectroscopy, the M peak represents the molecular ion, also known as the parent ion. This ion is generated when the molecule loses one electron, typically during the ionization process in the mass spectrometer. The molecular ion peak is crucial as it reflects the molecule's molecular weight, which aids in the identification of the substance.
The mass spectrometer functions by vaporizing the sample and ionizing it with a high-energy electron beam. The resulting charged ions, cations, are then deflected by a magnetic field, and the deflection depends on their mass-to-charge ratio. Ions are detected and shown on a mass spectrum plot, where the peak height correlates with the ion concentration.
Therefore, the correct answer to the student's question is a) Molecular ion (parent ion).