CHEMISTRY: Ksp related questions, very confused, plz help me

1.) Calculate the solubility product constant for silver iodide, which has a molar solubility of 1.2 × 10−8 mol/L.
----I thought the answer would be 2.4 x 10-8 but that's not even one of the answer choices....

2.) Pure water is saturated with PbCl2. In this saturated solution:
1. [Pb2+] = [Cl−]
2. [Pb2+] [Cl−] = Ksp
3. 2 [Cl−] = [Pb2+]
4. Ksp = [Pb2+]
5. [Pb2+] = 0.5 [Cl−]

3.) CaCO3 (100.1 g/mol) has a solubility of 0.018 g/100 mL in water at 35C. What is the value of Ksp at this temperature?

1)ksp = [Ag][I]

[Ag]=[I] = 1.2 x 10^-8

ksp= (1.2 x 10^-8)*(1.2 x 10^-8)
= 1.44 x 10^-16

2) I think the answer is 3.

3) (0.018g/100ml) / (100.1 g/mol)
= 1.798 x 10-4 mol/100mL *(1000mL/1L)
= 1.798 x 10-3 mol/L

ksp = [Ca]*[CO3]

[Ca] = [CO3] = 1.798 x 10-3 mol/L
ksp = 1.798 x 10-3 mol/L * 1.798 x 10-3 mol/L
= 3.23 x 10-6