help me please!!! buat besok nih, tq

1. Ksp PbI2 = 4s^3 = 7x10^-9
Ksp PbI2 = [Pb^2+] [I-]^2
   7X10^-9 = [ 2x10^-1] x [I-]2
      [I-] = 7x10^-8 M 
PbI2 ---> Pb2+ + 2I-
[PbI2] = 1/2 x 7x10^-8 = 7/2 x 10^-8 M