AP EAMCET201921 Apr 2019Evening ShiftChemistrySolid StateActual
A compound is formed from elements X and Y . The atoms of Y (anions) form a ccp lattice. The atoms of X (cations) occupy half of the octahedral voids and half of tetrahedral voids. What is the formula of the compound?
Options
- AX 3 Y 2
- BX 2 Y 3
- CXY
- DX 4 Y 3
Correct answer
A. X 3 Y 2
Step-by-step solution
The atoms Y form a CCP lattice means atoms are present at corners as well as the face centre. So, the number of atoms of Y present in the unit cell = 4 Number of tetrahedral voids present in CCP = 8 Number of octahedral void present in CCP = 4 So, the number of atoms of X present in the unit cell = 1 2 × 8   + 1 2 × 4   =   4 + 2   = 6 So, formula of unit cell : X   :   Y   = 6 : 4   X   :   Y   =   3 : 2 i . e .   X 3 Y 2