Solid State - Result Question 10

####10. At 100C, copper (Cu) has FCC unit cell structure with cell edge length of x\AA. What is the approximate density of Cu (in g cm3 ) at this temperature?

[Atomic mass of Cu=63.55u ]

(2019 Main, 9 Jan II)

(a) 211x3

(b) 205x3

(c) 105x3

(d) 422x3

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Answer:

Correct Answer: 10. (d)

Solution:

  1. For fcc, rank of the unit cell (Z)=4

Mass of one Cu-atom, M=63.55u

Avogadro’s number, NA=6.023×1023 atom

Edge length, a=x\AA=x×108cm

density (d)=Z×MNA×a3

=4×63.556.023×1023×(x×108)3=422.048x3gcm3



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