Read the following passage and answer the next five 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 d5 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 d5. Which transition metal is an exception ?
Answer & explanation
Correct answer: option 4
The correct answer is Option (4) → Mn
The melting points of transition metals rise to a maximum at about d5 because more unpaired d electrons take part in metallic bonding. In the 3d series the maximum should be at Cr or Mn, but manganese (and technetium in the 4d series) shows an anomalously low value. Its half-filled 3d5 configuration is very stable, so the d electrons are held tightly and take less part in metallic bonding.
Option (1) Ti — Fits the trend.
Option (2) V — Fits the trend.
Option (3) Cr — Fits the trend. It is near the expected maximum.
Option (4) Mn — The exception. Its melting point is anomalously low.
NCERT (2026-27 edition):
Physical Properties – …
