The ksp of iron(ii) hydroxide, fe(oh)2, is 4.87 × 10-17. calculate the molar solubility of this compound.

When iron hydroxide dissolves, it dissociates as follows
Fe(OH)₂ --> Fe²⁺ + 2OH⁻
molar solubility is the number of moles of solute that can be dissolved  is a 1 L solution
if molar solubility of Fe(OH)₂ is x then molar solubility of Fe²⁺ is x and OH⁻ is 2x
the solubility product constant - ksp formula is ;
ksp = [Fe²⁺][OH⁻]²
ksp = (x)(2x)²
ksp = x * 4x²
ksp = 4x³
ksp = 4.87 x 10⁻¹⁷
4x³ = 4.87 x 10⁻¹⁷
x = 2.30 x 10⁻⁶ M
molar solubility of Fe(OH)₂ is 2.30 x 10⁻⁶ M

The density of water is 1 g/cm cubed and in order for the pebble to sink its density has to be greater than the density of water and in order for the twig to float its density has to be less than the density of water