Question

Silver iodide has the same structure as zinc sulfide and its density is $5.67gc{m}^{-3}$. The edge length of the unit cell is:

• A. $4.50\mathring{A}$
• B. $5.50\mathring{A}$
• C. $6.50\mathring{A}$
• D. $7.50\mathring{A}$

Answer 1

Answer: (C)

$6.50\mathring{A}$

$Z_{eff}=4;\rho =5.67g/c{m}^3;M_A=108+127=235$

$\rho =\frac{Z\times M_A}{N_A\times a^3}$

$a^3=\frac{4\times 235}{5.67\times 6.02\times {10}^{2}3}$

$a^3=27.54\times {10}^{-23}=275.4\times {10}^{-24}$

$\Rightarrow a=6.50\mathring{A}$