The percent of histidine side chains would be deprotonated at pH 7.5 is 5.77 %.
<h3>What is pKa?</h3>
The term pKa refers to the negative logarithm of the acid dissociation constant (Ka). The pH is the negative logarithm of the hydrogen ion concentration.
Hence;
Ka = Antilog (-6) =
[H^+] = Antilog (-7.5) = 
We now have to use the formula;
α = ![\sqrt{} \frac{Ka}{[H^+] }](https://tex.z-dn.net/?f=%5Csqrt%7B%7D%20%5Cfrac%7BKa%7D%7B%5BH%5E%2B%5D%20%7D)
α = 
α = 5.77 %
Hence, the percent of histidine side chains would be deprotonated at pH 7.5 is 5.77 %.
Learn more about percent dissociation: brainly.com/question/12273293
Answer:
it's SN1 reaction,
it's takin double step to complete,first formation of carbocation and then attack of reagents,so it's SN1!