A compound MpXq has cubic close packing (ccp) arrangement of X. Its unit cell structure is shown below. The empirical formula of the compound is
(A)MX
(B)MX2✓ Correct
(C)M2X
(D)M5X14
Answer: (B)
Solution
From the unit cell structure: X atoms are at corners (8 × 1/8 = 1) and face centers (6 × 1/2 = 3), giving a total of X = 1 + 3 = 4. M atoms are at edge centers (4 × 1/4 = 1) and body center (1), giving a total of M = 1 + 1 = 2. The unit cell formula is M2X4, which simplifies to the empirical formula MX2.
JEE Advanced · 2012 · 08 Apr 2012 · Paper 1 · Single correct option