① The density of aluminum (Al) is ρ (Al) =2.69g/cm? ;

② The density of zinc (Zn) is ρ (Zn) =7. 14g/cm? ;

③ The density of magnesium (Mg) is ρ (Mg) = 1.74g/cm? ;

④ aluminum alloy density ρ (aluminum alloy) =2.63~2.85g/cm? ;

⑤ magnesium alloy density ρ (magnesium alloy) = 1.75~ 1.90g/cm? ;

⑥ zinc alloy density ρ (zinc alloy) =6.3~6.7g/cm? .