Question

a metal crystallizes in two cubic phases FCC and BCC whose unit cell length are 3.5 A° and 3.0 A° the ratio of their densities is

Answer 1

Answer: Density of fcc = Z1×At.massAv.no×V1

and density in bcc =Z2×At.massAv.no.×V2

dfccdbcc=Z1Z2×V2V1

For fcc

Z1=4;V1=a3=(3.5×10−8)3

For bcc

Z2=2;V2=a3=(3.0×10−8)3

dfccdbcc=4×(3.0×10−8)32×(3.5×10−8)3

=1.259

Answer 2

Answer:

d is directly proportional to l^3

d1/d2 =( 3.5/3)^3