solid state Questions

Assertion (A): In a particular point defect, an ionic solid is electrically neutral, even if few of its cations are missing from its unit cells.Reason (R): In an ionic solid, Frenkel defect arises due to dislocation of cation from its lattice site to interstitial site, maintaining overall electrical neutrality.

Copper crystallises in $fcc$ unit cell with cell edge length of $3.608\times 10^{-8}\text{cm}$. The density of copper is $8.92{\text{g cm}}^{-3}$. Calculate the atomic mass of copper: