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Structure of a mixed oxide is cubic close - packed (c.c.p). The cubic unit cell of mixed oxide is composed of oxide ions. One fourth of the tetrahedral voids are occupied by divalent metal A and the octahedral voids are occupied by a monovalent metal B. The formula of the oxide is:

  • Option 1)

    A2BO2

  • Option 2)

    A2B3O4

  • Option 3)

    AB2O2

  • Option 4)

    AB O2

 

Answers (1)

best_answer

As we learnt in

No. of atoms(z) for end centered unit cell -

Lattice point: at corners and one pair of opposite face centers.

For  end centered cubic, z=2

- wherein

 

 

 

Given that its a c.c.p and unit cell is composed of oxide ions.

So, O^{2}^{-} ions=4

Octahedral voids=\frac{1}{2} tetrahedral\ voids= \frac{1}{2}\times 8=4

\therefore A=\frac{1}{4}\times 8=2

    B = 4

Summing up, the formula is A B_{2}O_{2}

 


Option 1)

A2BO2

Incorrect option

Option 2)

A2B3O4

Incorrect option

Option 3)

AB2O2

Correct option

Option 4)

AB O2

Incorrect option

Posted by

prateek

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