Question

An element X (atomic weight $=24g/mole$ ) forms face centred cubic lattice. If the edge length of the lattice is $4\times 10^{-8}cm.$ and the observed density is $2.40\times 10^{3}kg/m^3$ The $\%$ age occupancy of lattice point by $X$ element is-

• A. $96\%$
• B. $84\%$
• C. $75\%$
• D. $2.5\%$

Answer 1

Answer: (A)

$\rho =\frac{Z\times M}{a^3\times N_A}=\frac{4\times 24}{{\left(4\times 10^{-8}\right)}^3\times 6\times 10^{23}}$

$=\frac{4\times 24}{64\times 10^{-24}\times 6\times 10^{23}}$

$\rho =2.5g/c{m}^3$ or $2.5\times 10^{3}kg/m^3$

$\%$ age occupancy $=\frac{2.4\times 10^3}{2.5\times 10^3}\times 100=96\%$