Water has a density of 1000 kg/m3 by standard definition at its temperature of maximum density 3.98 Â°C and at 0% salinity. Scientists and engineers use water as a baseline for comparing the relative density of various materials. Water with a density of 1000 kg/m3 at 3.98 Â°C has a mass of 1000kg and a volume of 1 m3.
Spelt is a word. It is the past participle of spell. It is also a type of wheat, and therefore also a noun. It depends upon whether you are using British English (and Spelt is correct) or you are using American English.
Both, although some subscribe to spelt being used only as a simple past form, whilst others claim it should only be used to form the present/past perfect. Wait until some petty style manual takes sides then the Yanks amongst us will start screaming that that is the only possible way to use it, and always has been.