Structure along with ¹H-NMR is shown below.
Signal for Hₐ;
Based on multiplicity of of the peak, a Singlet peak (the only singlet peak present in spectrum) at 2.2 ppm was assigned to Hₐ. As the methyl group in not coupling with any other proton so it gave a singlet peak.
Signal for Hb;
Based on multiplicity of of the peak, a Quartet peak (the only quartet peak present in spectrum) at 2.4 ppm was assigned to Hb. As the methylene group in coupling with methyl group having three protons so it gave a Quartet peak.
Signal for Hc;
Based on multiplicity of of the peak, a Triplet peak (the only triplet peak present in spectrum) at 1.1 ppm was assigned to Hc. As the methyle group in coupling with methylene group having two protons so it gave a Triplet peak.