P2O5 is formed between phosphorus and oxygen: why is the name Phosphorus pentoxide and not phosphorus oxide while Na2S is not Disodium sulfide but sodium sulfide?

Water (2510 g ) is heated until it just begins to boil. if the water absorbs 5.09×105 j of heat in the process, what was the initial temperature of the water?

Which set of characteristics best describes igneous rock? a) largest type of rock, made of organic matter, hardest type of rock b) least abundant type of rock, made of other rocks, made mostly of minerals c) found on all continents, contains wavy bands of stripes, contains fossils d) most abundant type in earth's crust, made of magma/lava, contains no fossils

Why is retrograde motion an apparent motion