If there were only three electron groups around an atom how would they be arranged

They would be arranged in a trigonal planar orientation.

If there were only three electron groups around an atom they tend to repel each other and gain a trigonal planar orientation. A molecule with three electron groups orients the three groups as far apart as possible. They adopt the positions of an equilateral triangle 120° apart and in a plane. The shape of such molecules is trigonal planar. An example is BF3:

trigonal planar orientation.

Explanation:

wher is the rest of the question

gas and precipitate r the correct answers