What is the ph of a solution containing 0.12mol/l of nh4cl and 0.03 mol/l of naoh (pka is 9.25)?

pH = 8.77

Explanation:

The reaction between Ammonium chloride and sodium hydroxide yield the following products depicted in the ICE table below:

Initial    0.12 M        0.03 M            -     -     -

Change -0.03 M    -0.03 M          +0.03 M

Eq         (0.12-0.03)   (0.03-0.03)  +0.03 M  

Therefore,

This is a buffer with pKa = 9.25

Based on the Henderson-Hasselbalch equation:

answer; i believe that the correct answer is (a) potassium(k)