Which one of the following has the lowest melting point?

Mn

The correct answer is Option (2) → Mn

To determine which metal among iron (Fe), manganese (Mn), chromium (Cr), and nickel (Ni) has the lowest melting point, we need to consider the properties of these metals and their respective melting points. Here’s a detailed analysis:

Melting Points of the Elements

The melting points for the elements in question are as follows:

Iron (Fe): Approximately 1538°C

Manganese (Mn): Approximately 1246°C

Chromium (Cr): Approximately 1907°C

Nickel (Ni): Approximately 1455°C

Understanding Melting Points

Melting point is a physical property that indicates the temperature at which a solid becomes a liquid. The melting point of metals is influenced by several factors, including:

Bonding Type: The strength of metallic bonds contributes to the melting point. Stronger bonds result in higher melting points.

Crystal Structure: The arrangement of atoms in the crystal lattice can affect how tightly the atoms are packed and how easily they can move apart.

Atomic Size: Generally, smaller atoms can pack closer together, which can lead to stronger interactions and higher melting points.

Analysis of Each Metal

Iron (Fe): Iron has a body-centered cubic (BCC) structure at room temperature, which contributes to its relatively high melting point due to strong metallic bonding.

Manganese (Mn): Manganese has a melting point significantly lower than that of iron. It adopts a BCC structure as well, but its atomic structure allows for weaker bonding compared to iron.

Chromium (Cr): Chromium has a very high melting point, attributed to its high density and the strong metallic bonds in its body-centered cubic structure.

Nickel (Ni): Nickel has a face-centered cubic (FCC) structure, which generally allows for a higher melting point than BCC structures. Its melting point is lower than chromium but higher than manganese and iron.

Conclusion

Comparing the melting points:

Iron (Fe): 1538°C

Manganese (Mn): 1246°C (Lowest)

Chromium (Cr): 1907°C

Nickel (Ni): 1455°C

Manganese has the lowest melting point among the four metals, due to its weaker metallic bonding and structure compared to the others.

Thus, the correct answer to the question is: Mn (Manganese), as it has the lowest melting point at approximately 1246°C.