Quick questions on Spectroscopy and chromatography - WJEC A-Level Chemistry

Proton ($^1\text{H}$) NMR gives the number of different proton environments (number of peaks), the relative numbers in each (integration), and neighbouring protons (splitting, by the $n+1$ rule). Carbon-13 NMR gives the number of different carbon environments.

Chromatography separates a mixture between a stationary and a mobile phase; components are identified by their retention factor ($R_f$) in TLC or retention time in gas chromatography, often coupled to mass spectrometry (GC-MS) for identification.

Forensic and anti-doping labs separate complex mixtures by gas chromatography then identify each component by its mass spectrum, the combined power of the two techniques. MRI from NMR. Medical magnetic resonance imaging is built on the same nuclear magnetic resonance physics used to read proton NMR spectra in the lab.

State what the molecular ion peak in a mass spectrum tells you. [1 mark]

State the approximate infrared absorption of a $\text{C}=\text{O}$ bond. [1 mark]

State what the number of peaks in a proton NMR spectrum represents. [1 mark]

State the splitting pattern expected for the $\text{CH}_2$ protons in an ethyl group. [1 mark]

A mass spectrum loses $15$ from the molecular ion. Suggest the group lost. [1 mark]