3. Please explain the mechanism to form a hydrogen bond and compare it with covalent bond. Explain why hydrogen bond is so important in maintaining a protein structure.(8%)

2. If we consider a 850 MHz NMR spectrometer, the resonance of 1H nuclear is 850MHz. calculate the energy that is required to make the transition from the lower energy state to the higher state. Meanwhile, please explain how to calculate the population ratio of molecules in the higher and lower states? (8%)