QJEEM21Chac51: JEE Main 2021 Chemistry - Class 12 JEEM21Chac51 Solution: The unit cell of copper corresponds to a face centered cube of…

Density of copper, $d = {{Z \times M} \over {{a^3} \times {N_A}}}$

Given, Z = 4, for fcc lattice,

M = 63.54 g mol ^{$-$ 1}

= 63.54 $\times$ 10 ^{$-$ 3} kg mol ^{$-$ 1},

a = 3.596 $\mathop A\limits^o$ = 3.596 $\times$ 10 ^{$-$ 10} m,

N_A = 6.022 $\times$ 10²³ mol ^{$-$ 1}

On putting given values, we get

$\Rightarrow d = {{4 \times (63.54 \times {{10}^{ - 3}})} \over {{{(3.596 \times {{10}^{ - 10}})}^3} \times (6.022 \times {{10}^{23}})}}$ kg/m³

$= 9076.26 \simeq 9077$ kg/m³