Compound A has the molecular formula C₄H₈O₂. Figure 1 gives the infrared spectra of compound A.

Table gives the chemical shifts and multiplicity data of the broad-band decoupled ¹³ C NMR spectra of compound A. The mass spectrum gives peaks at mass numbers 29, 43 and 88.

Table ¹³C NMR spectral data for compound A

(a) Calculate the number of double-bond equivalents in compound A.

(b) (i) From the infrared spectrum of compound A (Figure 1) use the correlation charts in the S205 Data Book to assign the most likely type of absorption bands (group below 3000 cm^-1 and group around 1750 cm^-1 ).

(ii) Use the 13 C NMR data provided in Table 1 to explain what information they give about the nature of the carbon atoms in compound A.

(c) (i) Based on your answers for parts (a) and (b) deduce the structure of compound A (giving brief reasoning). Give the systematic name for compound A.

(ii) Assign the peaks obtained by mass spectrometry from your structure of compound A.