An irregular hexagon
There are fewer obtuse angles than the other two kinds. There are the same number of acute and right angles and so the sum of the measures of the acute angles will be less than 5 right angles. The sum of two obtuse angles will be less than 5 right angles but may be less than, equal to, or more than 5 acute angles.
A rhombus.
There is no such thing as a 3d hexagon. Regular hexagons cannot form a 3d shape.
No. A hexagon can only have six sides. No more, no less.
1 vertex less than a hexagon is a pentagon. 2 angles more than a triangle is a pentagon.
An irregular hexagon
If 1 or 2 of the obtuse angles are 'bent into' the hexagon then you can do it.A hexagon has 720° sum of interior angles. If you have 2 right angles, then that's 180°, leaving 540° to be distributed over four angles. If the two acute angles are 89°, then that leaves 362° to be divided between two angles, so at least one of these two angles will need to be greater than 180°. Below is my text graphics attempt of one possibility (ignore the 'dot'). Note that both of the obtuse angles are greater than 180°:|\_/||__.|Look at the related link to play with different angle possibilities for polygons.
Angles less than 90 = actute Angles of 90 = right angle Angles more than 90 = obtuse Angles more than 180 = reflex
There are fewer obtuse angles than the other two kinds. There are the same number of acute and right angles and so the sum of the measures of the acute angles will be less than 5 right angles. The sum of two obtuse angles will be less than 5 right angles but may be less than, equal to, or more than 5 acute angles.
A rhombus.
There is no such thing as a 3d hexagon. Regular hexagons cannot form a 3d shape.
No. A hexagon can only have six sides. No more, no less.
It is a hexagon in which either one [or more] of the sides is of a different length from the rest or one [or more] of the angles is of a different measure from the rest [or both].
A pentagon?
The answer depends on how the hexagon is partitioned.
There is no shape with exactly 4 right angles and 2 congruent sides.A rectangle has 4 right angles and 2 pairs of congruent sides - 4 sides in all. But if the numbers in the question are not limiting, then there are many more shapes. An irregular hexagon with the following shape, will meet the requirements if its height is the same as its base.___|....\|......\___!_______|There are lots more shapes with more sides.