Given scientific fact as input, generate the question from this fact such that it can be answered from the input.

Ex Input:
When an atom gains or loses an electron it becames a(n) ion.

Ex Output:
When an atom gains or loses an electron it becames an?

Ex Input:
Gastro-esophageal sphincter sphincter is located at the stomach end of the esophagus and opens to allow the bolus to enter the stomach.

Ex Output:
Which sphincter is located at the stomach end of the esophagus and opens to allow the bolus to enter the stomach?

Ex Input:
Four is the most electron-pair bonds a nitrogen atom can participate in.

Ex Output:
What is the most electron-pair bonds a nitrogen atom can participate in?