JEE PYQ: Solid State Question 22
Question 22 - 2019 (11 Jan Shift 1)
A solid having density of $9 \times 10^3$ kg m$^{-3}$ forms face centred cubic crystals of edge length $200\sqrt{2}$ pm. What is the molar mass of the solid?
[Avogadro constant $\approx 6 \times 10^{23}$ mol$^{-1}$, $\pi \approx 3$]
(1) 0.0432 kg mol$^{-1}$
(2) 0.0216 kg mol$^{-1}$
(3) 0.0305 kg mol$^{-1}$
(4) 0.4320 kg mol$^{-1}$
Show Answer
Answer: (3)
Solution
Density $= \dfrac{Z \times M}{N_A \times a^3}$. $9 \times 10^3 = \dfrac{4 \times M}{\left(200\sqrt{2} \times 10^{-12}\right)^3 \times 6 \times 10^{23}}$. $M = 305.4 \times 10^{-4} = 0.0305$ kg/mol.
BETA
