I’ve never taken organic chemistry but I always hated classes where the discussion after getting test results went like this:
“Aw man, I got a 40.”
“That’s great, most people got 20s, that’s the highest score”
“Aw man, I got a 40.”
“That’s great, most people got 20s, that’s the highest score”
If a test is supposed to measure your mastery of material relative to others', and point out your areas of potential improvement, a test with a full range of scores from 0 to 100% seems most effective. A test with a range of 0-40 is, agreed, less effective; but still better than a range of 80-100: an overly hard test merely points out that everyone has room for improvement.