Question

# A mineral having formula $$AB_{2}$$ crystallises in the cubic close-packed lattice, with the $$A$$ atoms occupying the lattice points. Hence coordination number of $$A$$ and $$B$$ atoms are:

A
4,8
B
4,4
C
8,8
D
8,4

Solution

## The correct option is A $$4,8$$There are two types of closed -packed lattices-Hexagonal closed packed lattice and Cubic close-packed lattice.Only FCC lattice forms the cubic closed packed lattice.So, $$A$$ forms the FCC lattice $$\Rightarrow Z_{eff}=4$$$$B$$ occupies the tetrahedral voids $$\Rightarrow Z_{eff}=8$$Therefore, one atom of $$A$$ is surrounded by $$8$$ atoms of $$B$$ and $$B$$ will be surrounded by $$4$$ atoms of $$A$$.Coordination number of $$A=8$$Coordination number of $$B=4$$Therefore, the formula of the compound will be $$A_4B_8$$ Or $$AB_2$$Hence, the correct option is A. Chemistry

Suggest Corrections

0

Similar questions
View More

People also searched for
View More