Chemistry · EQUILIBRIUM

The ionization constant of a weak base \( \text{NH}_3 \) is \( 1.77 \times 10^{-5} \) at \( 298\text{ K} \). What is the ionization constant (\( K_a \)) of its conjugate acid \( \text{NH}_4^+ \)? (Given: \( K_w = 1.0 \times 10^{-14} \))

1. A
   \( 1.77 \times 10^{-9} \)
2. B
   \( 5.64 \times 10^{-9} \)
3. C
   \( 5.64 \times 10^{-10} \)
4. D
   \( 1.77 \times 10^{-10} \)