Question

In a cubic unit cell A atoms are at the corner, B atoms are at the face centre ,C atoms are at edge centre and D atoms are at body centre . If 25% of A,50% of B,75%of C is removed then calculate the molecular formula

Answer 1

Answer:

Initially, atoms effectively in the lattice are as follows:

A→8×

8

1

,B→6×

2

1

,C→1,D→12×

4

1

After the removal of atoms,

atoms left at the corners=8−4=4⇒A→4×

8

1

=

2

1

atoms left at the face center=6−2=4⇒B→4×

2

1

=2

atoms left at the body center=0⇒C→0

atoms left at edge center=12−2=10⇒D→10×

4

1

=2.5

ratio of A:B,C:D=0.5:2:0:2.5=1:4:0:5

Hence, compound formula is AB

4

D