2-Methylpentane and 4-methyl-2-pentanone are constitutional isomers with the molecular formula C6H12O.each shows a molecular ion peak in its mass spectrum at m/z 100. Spectrum A shows significant peaks at m/z 85,58,57,43,42. Spectrum B shows significant peaks at m/z 71,58,57,43,29. Assign each compound it's correct spectrum?