An element X (atomic weight =80 g / mol ) having fcc structure, calculate the number of unit cells in 8 g of X :

Question

An element X (atomic weight =80 g / mol ) having fcc structure, calculate the number of unit cells in 8 g of X : (A) 0.4 × N A  (B) 0.1 × N A  (C) 4 × N A  (D) N A / 40

Tardigrade Admin · Accepted Answer

Effective number of atom in a unit cell =4 Number of atom =(8/80) × N A ∴ Number of unit cell =(N A /10) × (1/4)=(N A /40).

Q. An element $X$ (atomic weight $= 80 g / m o l$ ) having fcc structure, calculate the number of unit cells in $8 g$ of $X$ :

$0.4 \times N_{A}$

$0.1 \times N_{A}$

$4 \times N_{A}$

$N_{A} /40$

Effective number of atom in a unit cell $= 4$

Number of atom $= \frac{8}{80} \times N_{A}$

$∴$ Number of unit cell $= \frac{N _{A}}{10} \times \frac{1}{4} = \frac{N _{A}}{40} .$

Q. An element X (atomic weight =80g/mol ) having fcc structure, calculate the number of unit cells in 8g of X :

0.4×NA​

0.1×NA​

4×NA​

NA​/40