Question

Copper has face centred cubic (fcc) lattice with inter-atomic spacing equal to $2.54\mathring{A}$. The value of lattice constant for this lattice is :

• A. $2.54\mathring{A}$
• B. $3.59\mathring{A}$
• C. $1.27\mathring{A}$
• D. $5.08\mathring{A}$

Answer 1

The correct option is B $3.59\mathring{A}$

Given,

Interatomic spacing $=2r=2.54\mathring{A}$

For FCC,

$4r=\sqrt{2}$ a,

where a is lattice constant

$2r=\frac{\sqrt{2}a}{2}=\frac{a}{\sqrt{2}}$

$a=2r\sqrt{2}$

$=2.54\times 1.414\mathring{A}$

$a=3.59\mathring{A}$

Hence, option B is ocrrect.