Key concept First calculate Ksp of all the metal halides, then compare it with already given value of Ksp Given, molar concentration, i.e. solubility (S) =0.000011mol∕L Ksp=39.5×10−20 (a) M2X4⇌2M++4X− Ksp =(2S)2×(4S)4=1024(S)6 =18.14×10−28 (b) MX4⇌M++4X− Ksp=(S)×(4S)4=256(S)5 =42.68×10−24 (c)M2X6⇌2M++6X− Ksp=(2S)2×(6S)6 =186624(S)8 =40×10−36 (d)MX3⇌M++3X− Ksp =(S)×(3S)3=27(S)4 =39.5×10−20 ∴ The correct formula of the metal halide is MX3.