When an atom of the unstable isotope na-24 decays, it becomes an atom of mg-24 because the na-24 atom spontaneously releases:
(1) an alpha particle
(2) a beta particle
(3) a neutron
(4) a positron

(2) a beta particle, because and atom "moves up" one place in periodic table, and such thing happens when beta decay occurs.

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.

True is ur answer : )