JEE PYQ: Solid State Question 19
Question 19 - 2019 (09 Jan Shift 2)
At 100$^\circ$C, copper (Cu) has FCC unit cell structure with cell edge length of $x$ $\text{\AA}$. What is the approximate density of Cu (in g cm$^{-3}$) at this temperature?
[Atomic Mass of Cu $= 63.55$ u]
(1) $\dfrac{205}{x^3}$
(2) $\dfrac{105}{x^3}$
(3) $\dfrac{211}{x^3}$
(4) $\dfrac{422}{x^3}$
Show Answer
Answer: (4)
Solution
We know that density $= \dfrac{Z \times M}{N_A \times a^3}$. Given that $Z = 4$ (fcc), $M = 63.5$ g, $N_A = 6 \times 10^{23}$, $a = x \times 10^{-8}$ cm. $d = \dfrac{4 \times 63.5}{6 \times 10^{23} \times x^3 \times 10^{-24}} = \dfrac{422}{x^3}$ g cm$^{-3}$.
BETA
