To identify the unknown compound using mass spectrometry, we need to analyze the given information and try to deduce the possible chemical formula and structure.1. Molecular ion peak M+ at m/z 146: This indicates that the molecular weight of the compound is 146.2. Major fragment peaks at m/z 120 and 105: These peaks suggest that the compound can lose fragments with masses of 26 and 41, respectively, during the fragmentation process.3. The molecular ion peak is four times more intense than the base peak: This suggests that the molecular ion is relatively stable and does not undergo extensive fragmentation.Now, let's try to deduce the possible chemical formula of the compound:A molecular weight of 146 can be achieved with a combination of carbon, hydrogen, oxygen, and/or nitrogen atoms. A common approach is to calculate the double bond equivalent DBE or the degree of unsaturation.DBE = 2C + 2 + N - H / 2Since we don't know the exact number of carbon, hydrogen, and nitrogen atoms, we can't calculate the DBE directly. However, we can make some educated guesses based on common organic compounds.One possibility is that the compound contains a benzene ring, which has a molecular weight of 78 and a DBE of 4. This would leave us with a remaining mass of 68 146 - 78 to account for.A common fragment that can be lost from a benzene ring is an ethyl group C2H5 with a mass of 29. However, this doesn't match the given fragment masses of 26 and 41. Another possibility is the loss of a CN group mass 26 and a C3H5 group mass 41 .Taking these fragments into consideration, we can propose a possible chemical formula for the unknown compound:C6H5 benzene ring + CN 26 + C3H5 41 = C10H10N 146 The unknown compound could be a derivative of aniline C6H5NH2 with a propyl group C3H7 attached to the nitrogen atom, forming N-propylaniline C10H10N .Please note that this is just one possible solution, and further analysis such as NMR, IR, or elemental analysis would be needed to confirm the identity of the unknown compound.