Earth has an iron-nickel core which gives us a magnetosphere. Based on this questionthis question that replaces our iron core with a mercury core, would we be likely get a magnetosphere?
Mercury is highly conductive and forms mercury(Hg ii) crystals at high pressures. At low temperatures and high pressures it becomes superconductive. Given the conductivity, mercury might form a magnetosphere but I'm just not sure.
What happens to the crust or how life might form on such a planet is outside the question scope but if you'd like to speculate on these topics or on how the planet was formed, you are welcome to do so.