All elements in the same group
a._have similar chemical proprieties
b._ aren't similar in any way
c._are in the same sate at room temperature
d._have the same boiling and freezing points

the dissociation of nickel hydroxide is follows:

the concentration of hydroxide ion is

the equilibrium constant value of nickel hydroxide is = 6.1 * 10^-^1^6 and thus equilibrium equation can be written as:

thus, concentration of ni is 0.23 * 10^-^4 mol /l