Ph meters measures ph indirect or direct

Asingle atom of an element has 21 neutrons, 20 electrons, and 20 protons. which element is it? ok o z

Which statement correctly describes metallic bonds? a. they form when certain atoms lose electrons and other atoms gain electrons. b. they involve an attraction between anions and cations. they always involvpoth a metal and a nonmetal. d. they can only form between atoms of the same element. e. they form because electrons can move freely between atoms.

Acontrol during an experiment. might change remains constant does not exist does change