Which elements are liquid at room temperature

Explanation:

Taking 25°C as the room temperature, there are only two elements that are remarkably  liquid at room temperature; they are bromine, Br, (a nonmetal) and mercury, Hg,  (a metal).

It is very surprisingly: the other 116 elements are either solid or gaseous at room temperature.

Nevertheless, a few degrees above 25° other elements will be liquid.

This is the case of:

This information, of course, is found in tables which are available in internet and some textbooks.

your answer is a. the enthalpy of formation for a pure element in its standard state is always positive.