Question

A compound forms hcp structure. What is the number of tetrahedral voids formed in 0.8 mol of it.

• A. \(4.818\times 10^{23}\)
• B. \(9.635\times 10^{23}\)
• C. \(7.227\times 10^{23}\)
• D. \(2.410\times 10^{23}\)

Hint:

There are two tetrahedral voids per atom in hcp.

Answer 1

The Correct Option is B

Step 1: Understanding the Concept:
In a close-packed structure (hcp or ccp), every atom has 2 tetrahedral voids and 1 octahedral void.

Step 2: Detailed Explanation:
Number of atoms in 0.8 mol = \(0.8 \times 6.022\times10^{23} = 4.818\times10^{23}\).
Number of tetrahedral voids = \(2 \times 4.818\times10^{23} = 9.635\times10^{23}\).
Option (A) is the number of atoms (one void per atom). Option (C) equals 1.5 voids per atom and (D) is a half void per atom, neither matches the 2 per atom rule.

Step 3: Final Answer:
Option (B), \(9.635\times10^{23}\).

Final Answer:
Tetrahedral voids are twice the number of atoms. \[ \boxed{\text{(B) }9.635\times10^{23}} \]