Aluminum is the lighter than mercury.
Mercury.
mercury
Mercury is the only liquid metal. Bromine comes under group 7 in the table and is therefore a Halogen. Bare in mind that this is only true at standard states.
Chemistry is a science; chemical properties are specific for each substance.
At "normal" temperatures, Mercury is denser than any of those substances ... slightly more so than lead, somewhat more so than copper, and a lot more so than aluminium.
Hydrogen
Mercury is the lightest planet, with a mass of 0.055 that of Earth.
Mercury is a pure substance, more specifically it is an element.
If Mercury (element) is heated then like every other substance it expands.
Mercury is an element and therefore a pure substance.
Mercury is an element and is therefore a pure substance. There are no other elements in it.