Question

If the edge length of a $KCl$ unit cell is $488pm$, what is the length of $KCl$ bond if it crystallises in the fcc structure?

• A. $122pm$
• B. $244pm$
• C. $488pm$
• D. $974pm$

Answer 1

Answer: (B)

$244pm$

As $KCl$ has rock salt like structure in which anions are present at corners and cations are present at edge centre.

So, edge length $a=2\times$ bond length of $KCl$

$488pm=2\times$ bond length of $KCl$

Therefore, bond length of $KCl=\frac{488}{2}$ pm $=244$ pm