Q1: The statement is true. A rhombus has four sides with the same length. The opposite sides are parallel. A square has four sides with the same length, parallel opposite sides and four right angles.
Q2: Statement D is correct. Squares and parallelograms are quadrilaterals as they are polygons with four sides. Opposite sides of a square and a parallelogram are parallel as the adjacent angles are supplementary. A trapezoid has one pair of parallel sides as it has two pairs of supplementary angles.
Q4: I do not agree with the statement. Not all parallelograms are squares. Parallelograms have two pairs of parallel sides. The opposite sides are of equal length and the opposite angles are of equal measure. A square has four sides with the same length, parallel opposite sides and four right angles. Parallelograms do not have four sides with the same length and four right angles. Thus, parallelograms do not necessarily have to be squares.