NEET Chemistry The Solid State Questions Solved


Compute the percentage void space per unit volume of unit cell in zinc fluoride structure.

1. 15.03%

2. 22.18%

3. 18.23%

4. 25.07%

(D) Anions occupy fcc positions and half of the tetrahedral holes are occupied by cations. Since there are four anions and 8 tetrahedral holes per unit cell, the fraction of volume occupied by spheres per unit volume of the unit cell is 

For tetrahedral holes, rc/ra = 0.225

{1+(0.225)3} = 0.7493

Void volume = 1-0.7493 = 0.2507/unit volume of unit cell.

% Void space= 25.07%

Difficulty Level:

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