It's called an Icosahedron
http://mathworld.wolfram.com/Icosahedron.html
Depends. What shape is it?
A polyhedron with 20 faces is called an icosahedron.
A pentagonal prism.
the net of a shape is how many sides of a shapeThe net of a solid shape is a flat arrangement of its faces faces which can be folded together to make the solid shape. See related links, below.
An decagonal prism.
Since a cube has 6 faces, you would be looking for a solid shape with only 2 faces and no such solid exists.
an isosehedron has 20 faces
There is no regular solid with 13 faces.
tetrahedron
Depends. What shape is it?
a sphere
A polyhedron with 20 faces is called an icosahedron.
A polyhedron (solid shape formed by plane faces) with four faces is called a tetrahedron.
Shape
A pentagonal prism.
the net of a shape is how many sides of a shapeThe net of a solid shape is a flat arrangement of its faces faces which can be folded together to make the solid shape. See related links, below.
A polyhedron with 20 faces is called an icosahedron.