The correct option is C 2
The equilibrium between the undissolved solid M(OH)x and the ions in a saturated solution can be represented by the equation :
M(OH)x (s)⇌Mx+ (aq)+x OH− (aq)
s xs
Here solubility is s=10−4
∴ Ksp=[Mx+][OH−]x
Ksp=s×(xs)x
Putting the values,
4×10−12=10−4×(x×10−4)x4×10−8=(x×10−4)x
By inspection, we can find that the relation will hold good
when x=2.