Which are prisms among the following ?
We know that a prism is a polyhedron, two of whose faces are congruent polygons in parallel planes and whose other faces are parallelograms. Therefore,
(i) A nail is not a prism.
(ii) An unsharpened pencil is a prism.
(iii) A table weight is not a prism.
(iv) A box is a prism.