Final answer:
The mass of an object remains the same when taken to a planet with twice the gravity of Earth, but its weight doubles because weight is the force of gravity on the object, and this force is twice as strong on a planet with double Earth's gravity.
Step-by-step explanation:
If an object is taken to a planet with twice the gravity of Earth, the mass of the object remains unchanged because mass is an intrinsic property of the object and does not depend on the gravitational field strength of the planet. However, the weight of the object would double because weight is defined as the force exerted on an object due to gravity, which is given by the formula = weight (W) = mass (m) < = gravitational acceleration (g). Since the gravitational acceleration would be twice as much, the weight of the object would correspondingly increase by a factor of two.