MX:MX2​:M3​X:​Ksp ​=S2=4×10−8⇒S=2×10−4Ksp ​=4S3=3.2×10−14⇒S=2×10−5Ksp​=27S4=2.7×10−15⇒S=10−4​Order of solubility is MX>M3​X>MX2​