An object has a mass of 250g what is the gravitational force of on the object by the earth

Gravitational forces ("weight") = (mass) x (acceleration of gravity)

On Earth's surface, acceleration of gravity = 9.8 m/s²

Weight of the object on Earth = (0.250 kg) x (9.8 m/s²)
                                               = 2.45 newtons
 
Weight of Earth on the object = (0.250 kg) x (9.8 m/s²)
                                               = 2.45 newtons

                                       (about 8.81 ounces)