Q4. (i) What is meant by the term ‘coordination number’?
(ii) What is the coordination number of atoms:
(a) in a cubic close-packed structure?
(b) in a body-centred cubic structure?
Q4. (i) What is meant by the term ‘coordination number’?
(ii) What is the coordination number of atoms:
(a) in a cubic close-packed structure?
(b) in a body-centred cubic structure?

(i) Coordination number is the number of nearest neighbours around a particle.
(ii) 

(a) coordination number of close-packed structure is 12

(b) coordination number of body centred cubic structure is 8