1.

Percentages of the free space in cubic close packed structure and is body centered packed structure and is body centered packed structure are respectively.A. 48% and 26%B. 30% and 26%C. 26% and 32%D. 32% and 48%

Answer» Correct Answer - C
For FCC or CCP
`4r=sqrt(2)arArr P.F.=(nxx(4)/(3)pir^(3))/(a^(3))`
`n=4,a=2sqrt(2)r`
`P.F.=(4xx(4)/(3)pir^(3))/((2sqrt(2)r)^(3))P.F.=74%`
Free space =100-74=26%
For BCC
`4r=sqrt(3)a`
P.F. `=(2xx(4)/(3)pir^(3))/((4)/sqrt(3)r)^(3)`


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