A compound shows a molecular peak in its mass spectrum at m/z 72 and the base peak at m/z 43. an infrared spectrum of this compound shows, among other absorption, four bands in the 2990-28590cm-1 range and a strongband at 171715 cm-1. There are no IR peaks at greater than 3000 cm-1. the 1H NMR spectrum contains a triplet at 1.08 ppm (3H), a singlet at 2.5 ppm (3H), and a quartet at 2.45 ppm (2h). the magnitudes of the splitting of both the quartet and triplet are identical. deduce the structure of this compound and assign all the NS, IR, and NMR peaks.