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F centre is an example of metal excess d...

F centre is an example of metal excess defect due to the presence of extra cations at interstitial sites. Zinc oxide is white in colour at room temperature, on heating it loses oxygen and turns yellow.
`ZnO overset("Heat")toZn^(2+)+(1)/(2)O_(2)+2e^(-)`
Now there is excess of zinc in the crystal and its formula becomes `Zn_(1+x)` O. the excess of `Zn^(2+)` ions move to interstitial sites and the electrons to neighbouring interstitial sites.
There are many solids which are difficult to prepare in the stiochiometric composition and contain less amount of the metal as compared to stiochiometric proportion. a typical example of this type is FeO which is mostly found with a composition of `Fe_(0.95)`. it may actually range from `Fe_(0.96)` O.
Q. In `Fe_(0.95)` O:

A

Metal excess defect is present

B

Metal deficiency defect is present

C

F-centre is present

D

All of the above are present

Text Solution

Verified by Experts

The correct Answer is:
B
Metal deficiency defect is present
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Knowledge Check

  • In a solid lattice, the cation has left a lattice site and is located at interstitial position, the lattice defect is:

    A
    interstitial defect
    B
    vacancy defect
    C
    Frenkel defect
    D
    Schottky defect

  • In a solid lattice, the cation has left a lattice site and is located at interstitial position, the lattice defect is:

    A
    interstitial defect
    B
    vacancy defect
    C
    Frenkel defect
    D
    Schottky defect

  • What are the formal charges of the atoms in the nitrite ion in the order of nitrogen, oxygen 1 and oxygen 2? overset(1)(O) = N - overset(2)(O)

    A
    0, 0,-1
    B
    0,-1,-1
    C
    -1,0,-1
    D
    -1,0,0

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