The key catalytic amino acids of the chymotrypsin active site in the free enzyme are: A. a serine, an aspartic acid with a deprotonated side chain and a histidine with a protonated side chain. B. a serine, an aspartic acid with a deprotonated side chain and a histidine with a deprotonated side chain. C. a serine, an aspartic acid with a protonated side chain and a histidine with a protonated side chain. D. a serine, an aspartic acid with a protonated side chain and a histidine with a deprotonated side chain. E. a serine, an aspartic acid, and a histidine; each of which has a deprotonated side chain.

The answer is the first option just took the test

Answerhund's rule;

First up write the aim
then write the materials reqd.
then the procedure which you follow
then observation
then conclusion
then you can write lab safety rules or precautions(you can avoid if u want).
lemme' give an example
aim: to observe the double displacement reaction
materials reqd: bacl2 and na2so4, test tubes and a dropper
procedure:
1. take bacl2 in a test tube and na2so4 in the other.
2. then pour bacl2 into na2so4 solution.
3. observe
observation:
you will see that a white precipitate is formed called baso4. along with that common salt or nacl is formed.
the equation is
bacl2+na2so4=baso4+2nacl
conclusion:
a double displacement reaction is observed.
hope it

I'm sorry but, is there a list of options?