Sleepsleep
There's plenty of nonsense, particularly my pet hate of terminology questions, in PPL/CPL/ATPL TK exams, but that isn't an example. Personally I must do a calculation involving fuel density most weeks, and this sort of built-in knowledge is important for carrying out quick sanity checks on my calculations, vital in ensuring I don't make gross errors.
(0.82 for AVTUR, 0.715 for AVGAS, and no I didn't need to look that up).