A buffer is formed by mixing 100 mL of 0.1 M NH4Cl with 50 mL of 0.3 M NH3. To this solution 12 mL of 0.1 M NaOH is added. What is the approximate pH of the new solution after neutralization? Assume a Kb of 1.8 × 10^-5 for the weak base.
1. 9.37
2. 4.48
3. 4.63
4. 9.52
5. 9.44