Question

Sodium crystallizes in bcc structure with radius 1.86 × 10⁻⁸ cm. What is the length of unit cell of sodium?

Options

• 5.26 × 10⁻⁸ cm

• 3.272 × 10⁻⁸ cm

• 7.44 × 10⁻⁸ cm

• 4.3 × 10⁻⁸ cm

Answer 1

4.3 × 10⁻⁸ cm

Explanation:

r = 1.86 × 10⁻⁸ cm

a = ?

For bcc structure, r = `sqrt3/4 "a"`

∴ `sqrt3` a = 4 r

∴ a = `(4"r")/sqrt3 = (4 xx 1.86 xx 10^-8  "cm")/sqrt3`

∴ a = 4.3 × 10⁻⁸ cm