An element (atomic mass = 125) crystallizes in simple cubic structure. If the diameter of the larges — Solid State Chemistry Question
Question
An element (atomic mass = 125) crystallizes in simple cubic structure. If the diameter of the largest sphere which can be placed in the crystal, without disturbing the crystal, is 366 pm and the density of crystal is 'd' $\text{g/cm}^3$, then the value of '300 d' is
💡 Solution & Explanation
In simple cubic, the largest sphere fits in the body-centred cubic void, with diameter $d_{void} = (\sqrt{3} - 1)a$. Given $d_{void} = 366 \text{ pm} \implies a(0.732) = 366 \implies a = 500 \text{ pm} = 5 \times 10^{-8} \text{ cm}$. Density $d = \frac{1 \times 125}{6 \times 10^{23} \times (5 \times 10^{-8})^3} = \frac{125}{75} = \frac{5}{3} \text{ g/cm}^3$. Thus, $300 d = 300 \times \frac{5}{3} = 500$. Therefore, correct answer is 0500.