elements a, b and c have following relations. b is in the same group as a and b’s period number is larger than a’s. c is in the same period as b and c’s atomic number is less than b’s. the relation of their atomic radii is:

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