Question

If a planet of given density were made larger, its force of attraction for an object on its surface would increase because of the greater distance from the object to the centre of the planet. Which effect predominates?

Answer 1

$g=G\frac{M}{R^2}=G\frac{\rho \frac{4}{3}\pi r^3}{r^2}=\frac{4}{3}G\rho \pi rg\propto \rho r$

Since $r$ is increased the value of acceleration dur to gravity unit increase.