Question

While eating at the restaurant, a hair was found in a bowl of potato soup

Answer 1

And the question is.. ? :I

Answer 2

I think a better phrase would be "Whilst eating at the restaurant, a piece of hair was found in the bowl of potato soup".

Since "while" is generally used for longer periods of time, "whilst" is a better substitute in this instance because it will not take an unreasonable amount of time to consume a bowl of soup. "Whilst" is generally used for shorter time periods. A good example of "while" would be... " I used to live there for a while" as clearly you would not live in a house at a fixed address for very short period (less than a day). Don't forget to add a comma between restaurant and "a" as it joins the two, and is easier on the eyes.

Furthermore, "a hair" is not terribly good English in this instance and even possibly illegal, and should also be substituted with "a piece"... or you could go one further and say "a strand" which describes the singular.

I hope this helps!