CIE Nov 2014 v3 Paper 4 Q8

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PMT 16 (a) Analysis of a sample of DNA showed that 33% of the nitrogenous bases present was guanine. Calculate the percentages of the other bases in this sample of DNA. adenine % cytosine % thymine % [2] (b) Many drug molecules are chiral, but are often produced as a mixture of optical isomers. (i) Suggest why a larger mass of the mixture is required than of a single optical isomer.(ii) Suggest a problem that might arise as a result of taking a mixture of optical isomers.[2]UCLES 2014 9701/43/O/N/14<br /> 17 (c) There are four structural isomers with the molecular formula C5H10O that are aldehydes. (i) Draw the structures of these aldehydes. PMT (ii) The NMR spectrum of one of these isomers contains four absorptions. Which isomer P, Q, R or S gives this spectrum? isomer(iii) Predict the number of absorptions that would be given by each of the other three isomers. isomer letter (P, Q, R or S) number of absorptionsUCLES 2014 9701/43/O/N/14 [6] [Total: 10] [Turn over<br />

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