prov:value
| - n group (F, Cl, Br or I); where X is a halogen group (F, Cl, Br or I); where X and Y are the same or different and are a halogen group (F, Cl, Br or I); where X and Y are the same or different and are a halogen group (F, Cl, Br or I); and where X is a halogen group (F, Cl, Br or I).
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