To identify the unknown compound X using the mass spectrometry data provided, we will analyze the molecular ion peak and the fragment ions.1. Molecular ion peak at m/z 172: This indicates that the molecular weight of the compound is 172 g/mol.2. Fragment ions at m/z 145 and 127: These peaks suggest that the compound has lost 27 and 45 mass units, respectively, during fragmentation.Now, let's analyze the mass differences between the molecular ion peak and the fragment ions:- Loss of 27 mass units 172 - 145 : This could be due to the loss of a CH3CO group 15 + 12 = 27 , which is a common fragmentation pattern for esters.- Loss of 45 mass units 172 - 127 : This could be due to the loss of a COOH group 12 + 16 + 16 + 1 = 45 , which is a common fragmentation pattern for carboxylic acids.Considering these fragmentation patterns, the unknown compound X could be an ester with a carboxylic acid group. One possible structure that fits the molecular weight and fragmentation pattern is ethyl benzoate C9H10O2 , which has a molecular weight of 166 + 6 = 172 g/mol.Ethyl benzoate C9H10O2 structure:- A benzene ring C6H5 with a molecular weight of 12*6 + 1*5 = 77 g/mol- An ester group COOCH2CH3 with a molecular weight of 12 + 16 + 16 + 12 + 1*3 = 95 g/molIn conclusion, based on the mass spectrometry data provided, the unknown compound X is likely to be ethyl benzoate C9H10O2 with a molecular weight of 172 g/mol.