An infinite number. Draw one and then keep moving its parallel side further and further away.
And you did not even look at the trapeziums that could be generated by varying the length of that side.
Usually none but it's quite possible for it to have two.
720 degrees * * * * * The internal angles of any quadrilateral add to 360 degrees.
Each trapezium has 4 sides so 3 of them have 12 sides.
There are 3 different types: ordinary, isosceles and right which has 2 right angles
2
As many or as few as you want. You choose a length and a rhombus with sides of that length can be drawn.
Infinitely many.
One pair.
Usually none but it's quite possible for it to have two.
720 degrees * * * * * The internal angles of any quadrilateral add to 360 degrees.
Each trapezium has 4 sides so 3 of them have 12 sides.
A trapezium has two diagonals.A 4 sided quadrilateral trapezium has 2 diagonals.
There are 3 different types: ordinary, isosceles and right which has 2 right angles
2
There are infinitly many types. However some broad (and not necessaryly exclusive) classes of trapezia are Right trapezia (with at least 1 right angle) Isoceles trapeziea (the non parallel sides are equal in length) parallelograms (both pairs of sides are parallel)
The meaning of this question is not clear. A square is a two dimensional reqular quadrilateral - a flat shape with four sides of equal length. The lengths can have any value. As such a square does not have a base, so it is not clear how the base of a square can have any length.
You need at least four triangles, or at least three trapeziums. Or two triangles and one trapezium.