Kepler’s law states that
I. the orbit of planets are elliptical with one focus at the sun.
II. A line connecting the sun and a planet sweeps out equal areas in equal times and
III. the square the period of a planet’s orbit is proportional to the cube of its semi-major axis.
Which of these laws would remain true if the force of gravity were proportional to $\frac{1}{r^{2.5}}$ , rather then $\frac{1}{r^2}$ ?