3. The mass spectrum of an unknown compound shows a molecular ion peak at m/z = 206, with a relative intensity of 100. The M + 1 peak has a relative intensity of 15.11 and the M + 2 peak has a relative intensity of 4.40. What is the molecular formula for the unknown?
4. The mass spectrum of an unknown compound shows a molecular ion peak at m/z = 113, with a relative intensity of 100. The M + 1 peak has a relative intensity of 7.05 and the M + 2 peak has a relative intensity of 0.21. A major IR stretch for the compound is observed at 1654 cm-1. Provide a reasonable molecular formula and a structure for the unknown.