Question

In the basic $CsCL$ crystal structure, $Cs^+$ and $Cl^-$ ions are arranged in a bcc configuration as shown in the figure. The net electrostatic force exerted by the eight $Cs^{+}$ ions on the $Cl^-$ ions is

• A. $\frac{1}{4 \pi\varepsilon_{0}} \frac{4e^{2}}{3a^{2}}$
• B. $\frac{1}{4 \pi\varepsilon_{0}} \frac{16e^{2}}{3a^{2}}$
• C. $\frac{1}{4 \pi\varepsilon_{0}} \frac{32e^{2}}{3a^{2}}$
• D. zero

Answer 1

Answer: (D)

zero

Answer 2

The given crystal structure is a body centered cubic structure. The electrostatic force. $F=\frac{1}{4 \pi \varepsilon_{0}} \frac{q_{1} q_{2}}{r^{2}}$ due to one $Cs ^{+}$ion is balanced by diagonally opposite $Cs ^{+}$ion. Hence, net electrostatic force on $Cl ^{-}$ion due to eight $Cs ^{+}$ions is zero.