Which isotope is used for a standard for all other atomic masses?

Well to my expert knowledge and my exquisite calculations i think the the negative ion # 412 is the key to sucess

Non metal is an element or substance that is not a metal metal is a solid material that is typically hard, shiny, malleable, fusible, and ductile, with good electrical and thermal conductivitymetalloid is an element (e.g., germanium or silicon) whose properties are intermediate between those of metals and solid nonmetals. they are electrical semiconductors.

Polygon is ur