No, a cube cannot have an octagonal cross-section.
Rectangle
The cross section of a pyramid shrinks from the shape of the base down to a point as you move along its axis from the base to the apex. The cross section of a prism is constant along its axis.
It is a triangle.
A hexagon.
No, a cube cannot have an octagonal cross-section.
Cross section of a Cube90 Degree Vertical & Horizontal cross sections of a Cube are square. Brahmajyothi
It is a square.
A square
Infinitely many.
Yes it can.
Rectangle
A cylinder has a circular cross section that is parallel to its base.
Yes, but not a regular one.
It will be the same shape as a square
The cross section of a pyramid shrinks from the shape of the base down to a point as you move along its axis from the base to the apex. The cross section of a prism is constant along its axis.
It will be one of:a triangle if where the cross section cuts the base is through two adjacent sides;an irregular quadrilateral if where the cross section cuts the base is through two opposite sides but not parallel to a side of the base; ora trapezium if where the is the cross section cuts the base is parallel to a side of the base.