D.) closeness of a measurement to an accepted value
That is accuracy not precision.
I think that it is helium, but not 100% sure
The traditional method is to heat the compound in an oven, on a hot plate or over a Bunsen burner. Waters of hydration are loosely bound in the compound and can be driven off at temperatures below the melting point of the compound. So the answer is heating.
Yes all the atoms have zero oxidation
