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JEE Main levelOne or more correct optionsDifficulty 2 of 3ss067

Which of the following statements about a bcc lattice of identical atoms are correct?

  1. AAtoms touch along the body diagonal, so .
  2. BThe coordination number is 8.
  3. CIt has 2 atoms per unit cell.
  4. DThe packing efficiency is 74%.

Answer: A, B, C

Corners give 1 and the body centre gives 1, so 2 atoms per cell. Each atom touches 8 neighbours and contact is along the body diagonal, . The packing efficiency is 68%, not 74% (74% belongs to fcc/hcp).
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