Hint: We know that mercury is the only metal that is liquid under normal temperature and pressure conditions. Mercury is a mediocre heat conductor but a good electrical conductor. Mercury has a special electron structure that makes it behave similarly to noble gas components when an electron is removed. Mercury forms unstable bonds as a result, and is a liquid at room temperature.
Complete answer: Mercury is the only metal that can be found in liquid form. Therefore mercury is heated by conduction rather than convection, which is the case for most liquids. Mercury is only found in liquid form because of its peculiar electronic structure. Mercury has a high resistance to electron elimination, which makes the bonds weak. Hence, mercury is heated by the method of conduction.
Additional Information: The vapour form of elemental mercury is easily ingested by inhalation and travels through the alveoli into the bloodstream and red blood cells. The catalase-enzyme in the erythrocytes converts it to Hg2+ there. As a result, elemental vapour easily penetrates the central nervous system and crosses the blood-brain barrier. It can affect the neurological, digestive, and immune systems, as well as the lungs and children, and can be lethal.
Note: It is important that we remember mercury has a high resistance to electron elimination, which makes the bonds weak. Mercury has the ability to transfer electrons in its condensed state (liquid or solid). When mercury is heated, it reacts with oxygen in the air to form mercury oxide, which decomposes as the temperature rises.