Given scientific fact as input, generate the question from this fact such that it can be answered from the input.
One example: Earth rotates on its axis once times in one day.
Solution is here: How many times does Earth rotate on its axis in one day?
Explanation: The given output correctly poses a question based on the scientific fact given.

Now, solve this: When we move down a group of elements on the periodic table, their electronegativity it decreases.
Solution:
When we move down a group of elements on the periodic table, what happens to their electronegativity?