Asubstance is tested and is found to have the following physical properties: high electrical conductivity malleability high luster the substance is most likely a a. metal b. metalloid c. nonmetal d. cannot be determined without more data

The correct answer is A. Metal

Explanation:

Metals are chemical elements and materials characterized by their high electrical conductivity due to the structure of electron in them different from nonmetals that have a low electrical conductivity. Besides this, metals are characterized by high malleability and high luster, the malleability means they can change their shape without breaking and in the case of metals they can be made into sheets which make then highly malleable different from nonmetals and metalloids that do not show malleability; on the other hand, high luster means they look shiny which make them different from nonmetals that are not shiny and metalloids that can be shiny or not shiny. Thus, the substance with high luster, malleability, and electrical conductivity is a metal.

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