Answer:
The shape of the cross section that is formed on this slicing is:
A rectangle.
Explanation:
A pentagonal prism is a prism in which the two bases of the prism are in the shape of a pentagon and the five faces are in shape of rectangles.
Now when the slicing of the prism is done by a plane perpendicular to the base then the cross-section so obtained is similar to the face of the prism.
Hence, the cross-section so obtained is:
Rectangle.