If the density of earth is doubled keeping its radius constant, then acceleration due to gravity g is

The acceleration due to gravity is directly proportional to the density of a planet, assuming the radius remains constant. This means that if the density of a planet doubles, the value of gravity on its surface also doubles. For example, increasing a planet’s density while maintaining the same size results in a stronger gravitational pull.
This relationship highlights how changes in a planet’s internal composition, such as an increase in mass per unit volume, can significantly impact its gravitational force. Thus, doubling the density leads to a direct doubling of the gravitational acceleration experienced on the planet’s surface.

g = 4/3πGRp i.e, g ∝ p
If density is doubled, then the value of g also gets doubled.