CGPET 2018 Solved Paper

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.