Chapter 13, Problem 13.9P

The low-resolution mass spectrum of an unknown analgesic X had a molecular ion of 151. Possible molecular formulas include ${\text{C}}_{\text{7}}{\text{H}}_{\text{5}}{\text{NO}}_{\text{3}}$, ${\text{C}}_8{\text{H}}_9{\text{NO}}_2$ and ${\text{C}}_{10}{\text{H}}_{17}\text{N}$. High-resolution mass spectrometry gave an exact mass of 151.0640. What is the molecular formula of $X$?