Final answer:
The sphere with the weight of 40 Newtons has the greatest gravitational force because weight is directly proportional to the gravitational force exerted on an object.
Step-by-step explanation:
The true statement about the picture concerning spheres with different weights would be that 'The 40 Newton sphere has the greatest gravitational force'. Weight is a measure of the gravitational force exerted on an object, and this weight is calculated by multiplying the mass of the object by the acceleration due to gravity (approximately 9.80 m/s² near the Earth's surface). Therefore, the statement that spheres have only weight but no mass is incorrect, as weight is directly proportional to mass. The smaller the weight does not mean the greater the gravitational force; the opposite is true. We also cannot say that the gravitational forces are the same if the weights are different, as gravitational force is what we measure as weight in this context.
It's crucial to correct misconceptions regarding gravitational forces and weights. According to Newtons third law, the force that the Earth exerts on an object due to gravity is equal in magnitude and opposite in direction to the force that the object exerts on the Earth, regardless of their respective masses. Therefore, the 40 Newton sphere exerts and experiences the greatest gravitational force because it has the greatest weight.