This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Surgery
pKa of lidocaine: 
Select and explain. 
A. 8.1, B. 8.9, C. 7.8, D. 7.6
C: 7.8
Answer: C: 7.8 
Explanation: Lidocaine hydrochloride is very soluble in water and alcohol and soluble in chloroform, but it is insoluble in ether. Lidocaine hydrochloride has a pKa of 7.86. Gebauer et al. developed a method for the study of lidocaine and oxycodone stability in a rectal gel.
The dissociation constants (pKa) for popular local anesthetics used in dentistry are:
Mepivacaine 7.6
Etidocaine 7.7
Lidocaine 7.9
Prilocaine 7.9
Bupivacaine 8.1
Tetracaine 8.5
Procaine 9.1
Ref: Monheim’s Local anesthesia 1st  ed page no 130