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The density of KBr is 2.75g cm^(-3). The...

The density of KBr is 2.75g `cm^(-3)`. The length of the edge of the unit cell is 654 pm. Show that KBr has a face centred cubic structure.(`N_A=6.023xx10^(23) mol^(-)` at. mass : K=39, Br = 80]

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For KBr, M=39+80=119
`a=(654xx10^(-10))`cm
`d=2.75 "g/cm"^3`
`therefore rho=(ZxxM)/(N_0xxa^3)`
or, `Z=(rhoxxN_0xxa^3)/M`
`Z=(2.75xx6.02xx10^23xx(654xx10^(-10))^3)/119`
On solving Z=3.89=4
hence, it is a fcc lattice.
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AAKASH INSTITUTE ENGLISH-THE SOLID STATE -Assignment (SECTION - D) (ASSERTION-REASON TYPE QUESTION)
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  2. A : In NaCl structure, the interionic distance is a/2 (a = Unit cell e...

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  3. A : The co - ordination number of CaF(2) is 8 : 4. R : Ca^(2+) ion...

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  4. A : The number of spheres are equal to the number of octahedral voids ...

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  5. A : In Schottky defect, density of crystal decreases. R : Equal nu...

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  6. A : If a tetrad axis is passed through the unit cell of NaCl and all i...

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  7. A : A particle at the corner of CCP unit cell has (1)/(8)th of its con...

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  8. A : Glass belongs to the category of covalent network solid. R : U...

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  9. A : NaCl shows Schottky defect at room temperature. R : NaCl shows...

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  10. A : Fe(3)O(4) is ferrimagnetic at room temperature but becomes paramag...

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  11. A : In molecular solids the lattice points are occupied by the atoms o...

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  12. A : Silicon is insulator at 0 K but semiconductor at room temperature....

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  13. A : Amorphous solids are isotropic. R : Amorphous solids are not rig...

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  14. A : In NaCl coordination number of Cl^(-) ion is 6 but in CsCl coordin...

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  15. A : All crystals of same substance possess the same elements of symmet...

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  16. A : AgBr shows both Schottky and Frenkel defect. R : AgBr is a cry...

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  17. A : Number of carbon atoms per unit cell in diamond is 8. R : The ...

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  18. A : The coordination number of ionic compound depends upon radius rati...

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  19. A : Number of rectangular plane in a cubic crystal is 3. R : Recta...

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  20. A : ccp is more efficient than hcp. R : Packing fraction is differe...

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  21. A : Coordination number of both Na^(+) and Cl^(-) NaCl is 6. R : Se...

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