Which is the only metal whose natural form is liquid?

The correct answer is: (c) Mercury

Explanation:
Mercury (Hg) is the only metal that exists in a liquid state at room temperature (25°C). It is a heavy, silvery-white metal, known for its high density and toxic properties. Mercury remains liquid because of its unique electron configuration, which results in weak metallic bonding and hence a low melting point (−38.83°C).

Information Booster:
• Mercury is also called quicksilver due to its shiny, liquid appearance.
• It is widely used in thermometers, barometers, and electrical switches (though now limited due to toxicity).
• Mercury is toxic, and exposure to its vapors can harm the nervous system.
• Its atomic number is 80 and it belongs to the d-block elements.

Additional Information:
• Tin – A solid metal used in soldering and alloys; melts at 231.9°C.
• Sodium – A soft, reactive metal that is solid at room temperature; melts at 97.8°C.
• Iron – A strong structural metal, solid at room temperature; melts at 1538°C.