Use the ICE table approach as solution:
PbSO₄ --> Pb²⁺ + SO₄²⁻
I - 0 0
C - +s +s
E - s s
Ksp = [Pb²⁺][SO₄²⁻]
1.82×10⁻⁸ = s²
Solving for s,
s = <em>1.35×10⁻⁴ M</em>
C. Distance from Earth
The observed brightness of a star (the apparent magnitude) to an absolute magnitude, you need to know the distance [d], to the star. Alternatively, if we know the distance and the apparent magnitude [m] of a star, we can calculate its absolute magnitude [d].
*paraphrased from "COSMOS.com"
207 is the mass number. 82 would be the atomic number