Subject: Physical Chemistry · Chapter: Solid State Chemistry · Topic: Crystal Systems Lattices · Exam: CSIR-NET DEC 2015 · Marks: 2 · Difficulty: Medium
For a simple cubic crystal lattice, the angle between the [201] plane and the xy plane is
(a)less than 30°
(b)between 30° and 45°
(c)between $45^{\circ}$ and $60^{\circ}$
(d)greater than $60^{\circ}$
Answer
Answer (as printed): D
Explanation
$\cos\theta=\dfrac{h_{1}h_{2}+k_{1}k_{2}+l_{1}l_{2}}{\sqrt{h_{1}^{2}+k_{1}^{2}+l_{1}^{2}}\sqrt{h_{2}^{2}+k_{2}^{2}+l_{2}^{2}}}$$\theta \approx 63.43^{\circ}$, which is greater than $60^{\circ}$.