Question

Two metals are completely miscible with each other to form a continuous range of solid solutions only if: (A) Two metals must be similar in size—their metallic radii must not differ by more than 15%. (B) Both metals must have the same crystal structure. (C) The chemical properties must be similar particularly the same electronegativity. (D) Both metals must have the same electrical conductivity.

• A. (A) and (D) only
• B. (A), (B), and (C) only
• C. (A), (B), (C), and (D)
• D. (B) and (C) only

Hint:

The atomic size needs to be similar and the crystal structures should be same or similar to form a solid solution, the electronegativity needs to be similar for a uniform distribution in the solid solution.

Answer 1

The Correct Option is D

The Hume-Rothery rules describe the necessary conditions for forming a substitutional solid solution.
• Atomic size: The two metals should have similar atomic sizes, with metallic radii differing by not more than 15%.
• Crystal structure: They should have the same crystal structure for atoms to replace each other in the lattice.
• Electronegativity: The chemical properties should be similar, particularly their electronegativity, so that they bond with similar strengths to their neighbors in the crystal lattice.
• Electrical conductivity: Electrical conductivity is not a requirement for forming solid solution.
Therefore, B and C are correct conditions.