Chemistry: The Molecular Science (5th Edition)

$$K_c = 2.50 \times 10^{-29}$$
1. The coefficients are half as big (divided by 2). Therefore: $$K_{c2} = (K_{c1})^{1/2} = (6.25 \times 10^{-58})^{1/2} = 2.50 \times 10^{-29}$$