Question

Based on Free electron theory, the Hall coefficient for Sodium having BCC structure is : 
(Given, side of cube, \(a = 4.28\AA\)) 
 

• A. $3.86 \times 10^{-10} \text{m}^3\text{C}^{-1}$
• B. $-2.45 \times 10^{-10} \text{m}^3\text{C}^{-1}$
• C. $2.45 \times 10^{-8} \text{m}^3\text{C}^{-1}$
• D. $-1.96 \times 10^{-9} \text{m}^3\text{C}^{-1}$

Hint:

For alkali metals (Group 1 like Na, K), the Hall coefficient is always negative (because electrons dominate) and usually on the order of $10^{-10} \text{ m}^3/\text{C}$. This instantly eliminates positive options and vastly differing magnitudes. Remember BCC = 2 atoms/cell, FCC = 4 atoms/cell.

Answer 1

The Correct Option is B