Question 11 (Choice 2) - Chemistry CBSE Class 12 Sample Paper for 2022 Boards [Term 2] - Solutions to CBSE Sample Paper - Chemistry Class 12

On the basis of the figure given below, answer the following questions: 

(A) Why does Manganese has lower melting point than Chromium? 

(B) Why do transition metals of 3d series have lower melting points as compared to 4d series? 

(C) In the third transition series, identify and name the metal with the highest melting point. 

Answer

(A)

• When a substance melts, it releases energy as it’s interatomic bonds break . 
• The stronger the bond, the higher the melting point of the substance.
• Manganese has a half filled d-orbital configuration with all the electrons spinning in the same direction. This makes it stable and less likely to form bonds with other atoms. 
• It has low interatomic forces of attraction , which are easier to break .
• Hence, it has a lower melting point than Chromium.

(B) 

• Transition metals of 4d and 5d series have higher metallic character due to larger size of the atoms as compared to elements of 3d series.
• They make more and stronger metallic bonds , which require more energy to break .
• Hence, elements from the 4d and 5d series have higher melting points than those of 3d series.
  
  
  

(C) As seen from the given diagram, Tungsten has the highest melting point.