[M2+]×[X−]2\left[\mathrm{M}^{2+}\right]\times[\mathrm{X}^-]^2[M2+]×[X−]2
[M2+]2×[X−]\left[\mathrm{M}^{2+}\right]^2\times[\mathrm{X^-}][M2+]2×[X−]
[M2+]×[X−2]\left[\mathrm{M}^{2+}\right] \times\left[\mathrm{X}^{-2}\right][M2+]×[X−2]
[M2+]×[X−2]2\left[\mathrm{M}^{2+}\right] \times\left[\mathrm{X}^{-2}\right]^{2}[M2+]×[X−2]2