Question

Metal M ion form ccp structure.Oxide ion occupy 1/2 of tetrahedral void and 1/2 octahedral void.what is the formula of oxide?
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Answer 1

it is Magnesium, oxide is

Magnesium Oxide

Answer 2

The formula of the oxide is ${{M}_{2}}{{O}_{3}}$

Explanation:

• c.c.p structure is similar to that of f.c.c.

• Number of metal ions in f.c.c$=4$

• In this case number of oxide ions in tetrahedral holes $=8$

• In this case number of oxide ions in octahedral holes $=4$

• Given only half of the oxide ions occupy the tetrahedral holes.

• So the number of oxide ions in tetrahderal holes $=4$

• Given only half of the oxide ions occupy the octahedral holes.

• So the number of oxide ions in octahderal holes $=2$

• Total number of oxide ions$=4+2=6$

• So the formula is $\[{{M}_{4}}{{O}_{6}}={{M}_{2}}{{O}_{3}}\]$