Explain why NMR spectroscopy can detect hydrogen atoms in molecules.
Explain why hydrogen atoms are invisible to X-rays.
The molecular formula of the amino acid cysteine is $\text{C}_3\text{H}_7\text{O}_2\text{NS}$. Explain which of the atoms present would show the greatest absorption on exposure to X-rays.
How many protons are present in one molecule of $P$? Explain your answer.
When a little $\text{D}_2\text{O}$ is added to $P$, the absorption at $\delta 2.0$ disappears. Explain what this tells you about the group responsible for this absorption and why.
What does the absorption at $\delta 0.9$ tell you about the adjacent carbon atom?
What group(s) is/are responsible for the absorption at $\delta 0.9$?
Suggest a structure for $P$.
A mass spectrum was obtained of $R$. The ratio of the heights of the $M{:}M{+}1$ peaks was $9.3{:}0.5$. Show that there are five carbon atoms present in one molecule of $R$.
Predict the ratio of the heights of the $M{:}M{+}2{:}M{+}4$ peaks as a result of the two bromine atoms in the dibromide $R$. Show your working.
What is the molecular formula of $R$?