Based on the nuclear magnetic resonance NMR spectroscopy spectrum provided, compound X has a singlet at 3.8 ppm and a quartet at 1.2 ppm. This information suggests that the compound has two distinct types of protons in its structure.The singlet at 3.8 ppm indicates that there is a group of protons that are not coupled to any neighboring protons. This could be due to the presence of a methyl group CH3 or a methylene group CH2 next to an electronegative atom such as oxygen or a halogen.The quartet at 1.2 ppm indicates that there is a group of protons that are coupled to three neighboring protons. This is characteristic of a methylene group CH2 that is adjacent to a methyl group CH3 .Based on this information, the structure of compound X is likely to be an ethyl group CH3CH2- attached to an electronegative atom, such as oxygen or a halogen. Some possible structures for compound X include:1. Ethyl alcohol CH3CH2OH 2. Ethyl halides, such as ethyl chloride CH3CH2Cl , ethyl bromide CH3CH2Br , or ethyl iodide CH3CH2I To determine the exact structure of compound X, additional information such as mass spectrometry data or infrared spectroscopy data would be needed.