Calculate the Equilibrium Concentration of ZN^{₂ +} (aq) in a Solution

Multiple Choice

Calculate the equilibrium concentration of ZN^{₂ +} (aq) in a solution that is initially 0.0125 M Zn(NO₃) ₂ and 0.600 M NH₃.
Zn²⁺(aq) + 4 NH (aq) + Zn(NH₃) ₄ ²⁺(aq) K_f = 2.9 * 10⁹

A) 7.8 * 10^-12 M
B) 4.7 * 10^- M
C) 1.5 *10 ^{- 8} M
D) 2.5 * 10 ^{- 9} M
E) 2.9 * 10⁹ M