Question

In the mass spectra, alkanes give a series of peaks separated by 14 mass units

Answer 1

Answer:-

Alkanes pass through fragmentation process in mass spectrometer.  Every alkane differs from next alkane by CH₂ group. When fragmentation takes place the molecule of alkane becomes shorter as it losses CH2 group which has mass of 14 u. Hence, the peaks corresponding to every fragment of alkane molecule are separated by 14 mass units.