Answer:
RoHS applies to the following substances for electronic equipment and electrical appliances: lead, mercury, cadmium, hexavalent chromium, PBB (polybrominated biphenyls), and some PBDEs (polybrominated diphenyl ethers).
Space is filled with nothing.
Space is the absence of matter.
Hope this helped
The correct answer is a dichotomous key. Basically, you use the key to decide what species an organism is by looking at what traits it has, and if it doesn't have some traits you can instantly rule out a large number of species which brings you closer to your answer of what the species is that you're looking at.