Which one of the following elements exists in liquid state at room temperature?

Mercury is the only metal that exists in a liquid state at standard room temperature [2]. While most metals are solids due to high melting points and strong metallic bonding, mercury is a notable exception found in thermometers [1]. At a standard room temperature of approximately 25°C, only two elements in the periodic table are liquid: mercury (a metal) and bromine (a non-metal) [t1][t4]. Other metals like sodium and calcium are solids at room temperature; sodium is specifically described as a soft alkali metal that can be cut with a knife but remains solid under standard conditions [c4][c5]. Although elements like gallium and caesium have very low melting points and can melt near body temperature, mercury remains the primary metallic element that is liquid at 20-25°C [c4][t1].

Sources

1. [1] Science , class X (NCERT 2025 ed.) > Chapter 3: Metals and Non-metals > Table 3.1 > p. 39
2. [2] Science , class X (NCERT 2025 ed.) > Chapter 3: Metals and Non-metals > What you have learnt > p. 55