Assuming that you mean pentagon, not pentagon, the answer is simply that a truncated pyramid has a flat top which can support weight easily whereas a pentagon pyramid would require a very fine balancing act.
It can be.
pentahedron examples: tetrahedron with one truncated corner, square pyramid
truncated pyramid
The formula for the volume of a truncated square pyramid with height h, and top edge a cm and bottom edge b cm is V = 1/3*(a2 + ab + b2)*h.
depends on what kind of pyramid it is
It is just called a square pyramid, but its not square. Its only square on the bottom, so they call it a square pyramid, or you can simply just call it a pyramid because a pyramid is a pyramid.
A square pyramid is a pyramid whose base is in the shape of a square.
A cube, a rectangular solid (box) or any skewed version of these. Even a truncated pyramid (square base, four sides, but top cut off).
A square based pyramid is called a square pyramid
The tomb of the emperor, at Sikandarā, near Āgra, is of unique design, in the shape of a truncated square pyramid 340 feet (103 metres) on each side. It consists of five terraces, four of red sandstone and the uppermost of white marble. Begun about 1602, it was completed in 1613, during the reign of Akbar's son Jahāngīr.
The base of a square pyramid is a square. The pyramid has 4 faces making the base have four edges. SQUARE PYRAMID
a square based pyramid is a square at the bottom and a pyramid at the top