Question

If the moon were twice as massive, would the attractive force of Earth on the moon be twice as large?
What about the attractive force of the moon on Earth?

Answer 1

Those forces are equal and they are

F = G* (mass of moon)*(mass of Earth)/distance^2
so, if the Moon was twice as massive, the attractive force of Earth on the moon be twice as large and the attractive force of the moon on Earth would be both twice bigger