The idiom is a phrase that has a meaning different from the literal meaning of the words. Let's look at the statements provided:
1. Traffic was moving at a snail's pace.
2. The pancakes were bubbling on the griddle.
3. She made a small fortune in the computer chip business.
4. Welcome to the third meeting of the Mars Society.
The statement that contains an idiom is: "Traffic was moving at a snail's pace." This statement uses the idiom "at a snail's pace" to describe the slow movement of traffic. The phrase "at a snail's pace" is not meant to be taken literally but rather to convey the idea of something moving very slowly.
Therefore, statement 1 is the one that contains an idiom.
