instruction:
Given scientific fact as input, generate the question from this fact such that it can be answered from the input.
question:
Clear mucus is secreted before ejaculation to neutralize acidic urine remaining in the urethra.
answer:
What is secreted before ejaculation to neutralize acidic urine remaining in the urethra?


question:
Duplicating the results of an experiment process will most likely lead to the scientific acceptance of a hypothesis.
answer:
Which process will most likely lead to the scientific acceptance of a hypothesis?


question:
As the altitude decreases, the density of air decreases.
answer:

What happens to the density of air as the altitude decreases?