The first noble gas compound was prepared by ............

Explanation

**Step-by-Step Solution:**

1. **Understanding Noble Gas Compounds**: Noble gases are generally known for their lack of reactivity due to their complete valence electron shells. However, they can form compounds under certain conditions. The first noble gas compound was synthesized, which indicates that it is a compound containing a noble gas element and another element.

2. **Identifying the First Noble Gas Compound**: The first noble gas compound that was prepared involved the noble gas xenon. The compound was synthesized by combining xenon with another element, specifically fluorine, to form xenon difluoride (XeF2) and other compounds.

3. **The Scientist Behind the Discovery**: The scientist who successfully prepared the first noble gas compound was Neil Bartlett. He conducted experiments that demonstrated that xenon could form compounds, which was a significant discovery in the field of chemistry.

...