Which has the lowest value of the melting point (m.p.)?

Hg

The answer is (3), Hg.

Mercury (Hg) has the lowest melting point of the elements listed. Mercury melts at -38.83 °C, while the other elements have melting points of:

• Cesium (Cs): 28.44 °C
• Iron (Fe): 1538 °C
• Chromium (Cr): 1768 °C

The melting point of an element is the temperature at which it changes from a solid to a liquid. The melting point of an element is determined by the strength of the intermolecular forces between the atoms or molecules of the element. Mercury has the lowest melting point because it has the weakest intermolecular forces.

The other elements listed have stronger intermolecular forces, which means that they require more energy to melt.