Orbital velocty = sqrt(GM/r)
Mass and size of mercury is less than that of earth.
Mass is about 5.5% that of Earth and radius is about 38% that of Earth.
On Substituting the values in given formula we will get orbital velocity of mercury = 47.69km/s
Orbital velocity of Earth is 29.78km/s
Therefore,
Orbital velocity of mercury > Orbital velocity of Earth