Read the following passage and answer the questions based on it.

The transition metals are very hard and have low volatility. Their melting and boiling points are high. In any row, the melting points of these metals rise to a maximum at $d^5$ and fall regularly as atomic number increases. The high melting points of these metals are attributed to the involvement of greater number of electrons from (n-1)d in addition to ns electrons in the interatomic metallic bonding.

In any row, melting points of these metals rise to a maximum at $d^5$. Which transition metal is an exception?

Mn

The correct answer is Option (4) → Mn.

In the context of transition metals, it's important to understand how melting points generally trend across a series in the periodic table. Typically, the melting points of transition metals rise to a maximum at chromium (Cr) in the d-block series and then decrease for the subsequent elements.

Melting Point Trends in Transition Metals

1. Titanium (Ti): 

Melting Point: 1,668 °C

Behavior: Increases as you move across from left to right up to chromium.

2. Vanadium (V):

Melting Point: 1,910 °C

Behavior: The melting point continues to rise after titanium.

3. Chromium (Cr): 

Melting Point: 1,907 °C

Behavior: Reaches the maximum melting point in this series, displaying a very high melting point due to its stable metallic bonding and unique crystal structure.

4. Manganese (Mn):

Melting Point: 1,246 °C

Behavior: There is a notable decrease in melting point compared to chromium.

The Exception

In this trend, manganese (Mn) is often considered the exception as its melting point is significantly lower than that of chromium, even though it is positioned after chromium in the d-block series.

Conclusion

Given the information above, the transition metal that is an exception to the general trend of melting points rising to a maximum at chromium (Cr) is: Mn (Manganese).

This decline in melting point after chromium highlights how manganese behaves differently than its neighboring metals