The mass spectrum of compound X, C5H10O2, is recorded. The peak heights of the M and M+1 peaks are 22.65 and 1.25 respectively.

1. (a)(i)Use these data to show that there are five carbon atoms present in one molecule of X. Show your working.[1]
2. (a)(ii)The mass spectrum has a peak at m/e = 57. Complete the equation to show the fragmentation of X to produce this peak. [C5H10O2]⁺ → +[2]
3. (b)State the use of TMS and CDCl3 in NMR spectroscopy. • TMS • CDC13[1]
4. (c)(i)The proton NMR spectrum of compound X, C5H10O2, is shown. [Figure 8.c] By considering both the relative peak areas and their δ values, use the Data Booklet to • deduce the part of the molecule that produces the peak at δ2.2, • deduce the part of the molecule that produces the peaks at δ1.2 and δ3.5, • deduce the part of the molecule that produces the peak at δ4.0.[3]
5. (c)(ii)When reacted with aqueous alkaline iodine, X produces a yellow precipitate. Use this information and your answers to (c)(i) to suggest a structure for X.[1]
6. (d)Compound W is an ester with the molecular formula C5H10O2. The proton NMR spectrum of W contains only two peaks. The relative areas of these two peaks are in the ratio 9:1. Suggest a structure for this ester, W.[1]
7. (e)(i)Compound V is a carboxylic acid which contains a chiral centre. It also has the molecular formula C5H10O2⁻. Explain what is meant by the term chiral centre.[1]
8. (e)(ii)Suggest a structure for V.[1]

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