Question 1: This statement is justified.
A square is a rhombus because it has two pairs of opposite sides that are parallel and has four sides that are equal, just like a rhombus. The opposite angles are also the same. However, a rhombus need not be a square. Although both a square and a rhombus have internal angles that add up to 360°, the angles of a square has to be all 90° but the angles of a rhombus may not be 90°. Therefore, this statement is justified.
Question 2: D is correct.
A square and a parallelogram are quadrilaterals because they both have four sides.
Both the square and parallelogram have opposite sides that are parallel. The top and bottom side of the square and parallelogram are parallel and the left and right side of the square and parallelogram is also parallel.
A trapezoid only has one pair of parallel lines because the other two lines of a trapezoid are not parallel so it only has one pair.
Question 4: I do not agree with this statement. Not all parallelograms are squares because all the angles in the square is 90° but not all the angles in a parallelogram is 90°.