In a compound atoms of element $Y$ from ccp lattice and those of element $X$ occupy $2 / 3^{\text {rd }}$ of tetrahedral voids. The formula of the compound will be

JEE Main · 2008 · 27 Apr 2008 · Offline · Solid State

In a compound atoms of element

Y

from ccp lattice and those of element

X

occupy

2/ 3^{rd}

of tetrahedral voids. The formula of the compound will be

Answer: (A)

In a cubic close-packed lattice the

Y

atoms number four per unit cell, and such a lattice has twice as many tetrahedral voids, namely eight. Filling two-thirds of these with

X

places

\frac{2}{3} \times 8 = \frac{16}{3}

atoms of

X

against four of

Y

. The ratio

X : Y = \frac{16}{3} : 4 = 16 : 12 = 4 : 3

, so the formula is

X_{4} Y_{3}

JEE Main · 2008 · 27 Apr 2008 · Offline · Single correct option