How long would it take to deposit 15.0 g copper metal at the cathode of an electrolysis cell running with a current of 150 mA

if you're asking what comes out, it's steam.

it takes on an electronical energy

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