Which diagram represents a physical change, only?

Answer heart of american                  live in harmony                    hillsides of orchards                    blaze of color                    backdrop of pines;

Self-ionizes to form an equilibruium system in which [ h_{3} o^{+} ]=[ oh^{-} ]=10^{-7} m

D=m/v =57.9/3 = 19.3 g/cm^3