Hardnes or Hardness: How To spell?
The word Hardnes is misspelled against Hardness, a noun meaning "The cohesion of the particles on the surface of a body, determined by its capacity to scratch another, or be itself scratched;-measured among minerals on a scale of which diamond and talc form the extremes."
Hardness has double 'ss' in the end mispronounced as 's'Remember double 'SS' appears in the end of this word which should not be misspelled with single 'S'
Wrong Spelling:  hardne-s  Correct Spelling:  hardne-ss 
Explore spell check of Hardness to spell without errors.