Question

Both mercury and water are liquids at room temperature, why mercury good conductor of heat but not water?

Answer 1

On a microscopic scale, *conduction* occurs as rapidly moving or vibrating
atoms and molecules interact with neighboring particles, transferring some
of their kinetic energy. Heat is transferred by conduction when adjacent
atoms vibrate against one another, or as electrons move from one atom to
another.
As density decreases so does conduction.
Lesser density means larger
distance between neihbouring particles hence we'll have fewer collisions
between atoms. The latter means less conduction.
It's known that density of water is less than of mercury. Hence conduction
of water is less than of mercury