exactly 1
It depends on which type of cuboid we are talking about. If it is a CUBE (a special type of cuboid), then it has nine planes of symmetry. If it is a cuboid with length, width and height all different, then it has three planes of symmetry. If it is a cuboid with two equal measurements (say width and length), then it has five planes of symmetry.
There are 3 planes of symmetry in a rectange.
6 planes of symentry
Infinitely many.
four.
Your question lacks context. However, it is possible to label a point as point E on any plane you like. The letter is freely available.
1
1
There is only one such plane.
1
Infinitely many.
Infinitely many.
No, perpendicular planes intercept at only one point. Parallel planes do not intersect at all.
one
None.
exactly 1