If an atom’s mass number is 210 and its atomic number is 85, how many neutrons does it have?

Mass number is the total number of Protons and Neutrons. Simply subtract 85 from 210. 210-85=125 neutrons

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.