Sir can i find packing efficiency and empty space like this which i have send along with question for hcp

No. of spheres pe 21 In face-centred cubic structure (cubic close packipg). EIGURE127 FGURE 1.26 Volume of 2 spa A Fraction o- o oce 11. Sizes of As alread Dids present --- C (O Tetra Top view of face-centred cubic unit cell Face-centred cubiC unit cell The rad As sphere on the face centre is touching the spheres at the corners", evidently AC = 4r (Fig Bat from ight angled triangle ABC, 1e packin IfR is E R is AC=AB+BC=+a = a . 2a=4r or 4 a 2 olaie of the unit cell= a No. of spheres in the unit cell -s64 Sokuse of 4 spheres =4 Fraction In c hence w () (ia T sphere the ar occupied. ie, packing fractimon10Tr 13 32r/2 0-74 or % occupied 74 6 cubic packing, Hence, packing efficiency is 74%. as &packing ciiiciency of 74% Packing effcieney of hep and cep structures. Cubic close packing (cep) is same as face nitric Tha arther, cep and hep are equally efficient. He