To separate a mixture of hard candies and marbles, the most efficient method would be .

true

explanation:

it's c (engineer's do their work with mechanical stuff not on any living being)

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