The electron ionisation mass spectrum of a monofunctional compound showed no molecular ion signal in its EI spectrum, which was dominated by a primary fragment ion signal at m/z 73, accompanied by a satellite signal of 4.4% relative intensity. The chemical ionisation mass spectrum recorded under proton transfer conditions showed an analytically useful signal at m/z 89, accompanied by a satellite signal at m/z 90 of relative intensity 5.5%. No

bands were present in the 3400-3100 or 1800-1650 cm^-1 regions of the IR spectrum of the compound.

a State what information can be deduced from the absence of bands in the 3400-3100 or 1800-1650 cm^-1 regions of the IR spectrum.

b Deduce the compounds relative molecular mass and its molecular formula.

c Suggest a structure for the compound, interpret the signal at m/z 73 in the EI spectrum and explain why there is no molecular ion signal in the EI spectrum.