CHEMISTRY

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In the analysis of food, the nitrogen from the protein is sometimes converted into ammonia which is titrated against a strong acid. Given that the final NH3 concentration (approximate) is 0.2M and that pKa for NH4+ is 9.2, choose the best indicator for such a titration
A. phenolphthalein - pKa 9.2
B. thymol blue - pKa 8.9
C. methyl orange - pKa 3.7
D. bromothymol blue - pKa 7.0
E. methyl red - pKa 5.1

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