Determine the K₆ for NO₂⁻ at 25°C. The Kₐ for HNO₂ is 4.6 × 10⁴.
- 1 × 10⁻¹⁴
- 4.6 × 10⁻⁴
- 7.2 × 10⁻¹³
- 2.2 × 10⁻¹¹