Question

What is the value of Kb for CN⁻ at 25°C? The Ka for HCN is 4.9 × 10⁻¹⁰.
1) 2.0 × 10⁵
2) 2.041 × 10⁻⁵
3) 4.9 × 10⁻⁵
4) 2.0 × 10⁻⁵