The pH of a buffer solution made by mixing 25 ~mL of 0.02 M NH ₄ OH and 25 ~mL of 0.2 M NH ₄ Cl at 25^ is ( pK . of NH ₄ OH =4.8 )

Step-by-step solution

As a mixture of NH ₄ OH and NH ₄ Cl acts as a basic buffer, so its pH must be basic, (i.e., greater than 7), hence the answer must be 2 nd. It can also be find by calculations : aligned pOH & = p K_b+ [ salt ] [ base ] & =4.8+ 0.2 M 0.02 M & =4.8 10 pOH & =4.8+1=5.8 pH & =14- pOH =14-5.8=8.2 aligned