each edge of a cubic unit cell is 400 pm long. if atomic weight of the element is 120 and its density is 6.25 g/cm3. The crystal lattice is :

a) simple cubic   b)BCC

c) FCC                c) NONE

Asked by chandlerbong164 | 12th Apr, 2020, 07:22: PM

Expert Answer:

Option (b) is correct.
The crystal lattice is bcc.
Atomic weight, M = 120
NA = 6.022 × 1023 
Unit cell, a = 400 pm
                = 400 × 10-10 
We have,
straight d space equals space fraction numerator zM over denominator straight N subscript straight A cross times straight a cubed end fraction

6.25 space equals fraction numerator straight z cross times 120 over denominator 6.022 cross times 10 to the power of 23 cross times open parentheses 400 cross times 10 to the power of negative 10 end exponent close parentheses cubed end fraction

straight z space equals space 2

Answered by Varsha | 13th Apr, 2020, 02:14: PM