Centre of gravity of the given square PQRO lies at:

(2, –2)

Reason — As given figure is a square with side length of 4 units which is a uniform shape so it's centre of gravity lies on the point of intersection of it's diagonals and since diagonals of a square are equal to each other then it's centre of gravity lies on it's geometrical centre.

So,

Coordinates of C.G. = Coordinates of geometrical centre of the square PQRO = (2,-2)