✅ Answer: Mercury
📖 Explanation
Mercury is the only metal that naturally exists as a liquid at standard room temperature (around 20–25°C / 68–77°F). It has a melting point of –38.83°C (–37.89°F), which means it remains in liquid form in most everyday environments.
While gallium also comes close (melting at just 29.76°C / 85.57°F), it is still solid at normal room temperature and only melts when held in your hand. Sodium, on the other hand, is a soft solid metal and reacts violently with water—it is nowhere near liquid at room temperature.
Mercury’s combination of low melting point and high density makes it unique among metals, which is why it was historically used in thermometers, barometers, and scientific instruments.