A square is a rhombus because a rhombus and squares has parallel sides. A rhombus is not a square as squares have 4 right angles and a rhombus does not.
I think the answer is a trapezium since it has fulfilled all the requirements. Since it has a pair of opposite sides equal in length and the other pair not equal in length and a pair of opposite angles that are supplementary.
No, not all parallelograms are squares. Squares CAN be parallelograms but rhombuses CAN also be parallelograms. But since rhombuses are not squares, the statement is false.