A scalar quantity is a physical quantity that has only magnitude (size) and no direction. Therefore, the answer to the question is a physical quantity that only has a size. Momentum and force are vector quantities because they have both magnitude and direction. Acceleration and displacement are vector quantities when the direction is considered, but can also be scalar quantities when only the magnitude is considered. Distance, on the other hand, is a scalar quantity because it only has magnitude and no direction. So the answer to the question is Distance.