This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Proteins and Amino Acids, Subject name: Biochemistry
pKA=pH when: 
Select and explain. 
A. Solute is completely ionised, B. When the concentration of ionised and unionized form is same, C. Solute is completely unionized, D. All of the above
B: When the concentration of ionised and unionized form is same
Answer: B: When the concentration of ionised and unionized form is same 
Explanation: Ans. B. When the concentration of ionized and unionized form is sameThis question is an application of Henderson Hasselbalch equation.It ispH=pKa+log/ is concentration of ionised form is concentration of unionised form.When =, thenpH=pKa+log/pH=pKa+log1i.e.pH=pKa+0