Question

An alloy of Cu and Au will show complete miscibility as per Hume-Rothery if: (A) The metallic radii of the Cu and Au differs only by 12.5%.
(B) Cu and Au have the same crystal structure.
(C) The chemical properties of both the metals are similar.
(D) The number of valence electrons is different in both.

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

Hint:

The Hume-Rothery rules are important for determining the miscibility of metals in alloys. Key factors include atomic radii, crystal structure, and chemical properties.

Answer 1

The Correct Option is B

Step 1: Hume-Rothery Rules Application.
The Hume-Rothery rules establish the criteria for the formation of solid solutions between two metals in alloys. These criteria include:1. A difference in atomic radii not exceeding 12.5%.2. Identical crystal structures for both metals.3. Similar chemical properties between the metals.

Step 2: Option Evaluation.
- (A) Copper (Cu) and gold (Au) exhibit a 12.5% difference in metallic radii, fulfilling the first criterion.- (B) Cu and Au share the same crystal structure, thus satisfying the second criterion.- (C) The chemical properties of Cu and Au are analogous, meeting the third criterion.- (D) The number of valence electrons has minimal influence on miscibility in this specific scenario.

Step 3: Determination.
Consequently, option (2) is the correct choice, encompassing statements (A), (B), and (C) exclusively.