Question

Metallic gold crystallises in fcc lattice. The length of the cubic unit cell is a which is $4.07$ $\mathring{A}$. What is the closest distance (in $\mathring{A}$) between gold atoms?

• A. $3.3$
• B. $1.5$
• C. $2.9$
• D. $6.2$

Answer 1

The correct option is C $2.9$

As we know, in fcc, closest distance $=2r=\frac{a}{\sqrt{2}}=2.9\mathring{A}$

Hence, the closest distance between gold atoms is $2.9\mathring{A}$.