In a change, such as a change of state (e. g., from solid to liquid), the substance as a whole changes, but its underlying structure remains the same.

Physical

Reason: The reason why this is a physical change and not another type of change is that in a chemical change the actual substance would be change, and not just how it looks of feels. In the end of it water is melted ice and ice is frozen water. Both changes can also be reverted to get back the original form.

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