Answer:
<h2>The diagonal of the volumetric figure is 7 units long.</h2>
Step-by-step explanation:
The figure is attached.
Notice that the dimensions of the prism are

First, we need to find the diagonal of the rectangular face on the base, this diagonal of the base is part of the right triangle formed by the diagonal of the volume, that's why we need it.
Let's use the Pythagorean's Theorem

This diagonal of the base is a leg in the right triangle formed by the diagonal of the volume.
Let's use again Pythagorean's Theorem

Therefore, the diagonal of the volumetric figure is 7 units long.