Solution:
A quadrilateral which is a square has following properties:
1. All sides are equal.
2. All angles are of 90 degree.
3. Opposite sides are parallel.
4. Diagonals bisect each other at right angles.
5. Diagonals are equal.
So, if the quadrilateral does not satisfy any of the properties written above , then that quadrilateral is not a square.
Drawn the diagram of square below,
