Question

Which of the following crystal system has axes of equal length intersecting at 90-degree angles?

• A. Orthorhombic
• B. Cubic
• C. Tetragonal
• D. Hexagonal

Hint:

Crystal Systems Characteristics. Memorize the axial lengths and interaxial angles for the 7 crystal systems. Cubic: \(a=b=c, \alpha=\beta=\gamma=90^\circ\).

Answer 1

The Correct Option is B

Crystal systems are classified based on the lengths of the unit cell axes (a, b, c) and the angles between them (\(\alpha, \beta, \gamma\)).
- Cubic: \(a = b = c\); \(\alpha = \beta = \gamma = 90^\circ\).
(Axes equal, angles 90°) - Tetragonal: \(a = b \neq c\); \(\alpha = \beta = \gamma = 90^\circ\).
(Two axes equal, angles 90°) - Orthorhombic: \(a \neq b \neq c\); \(\alpha = \beta = \gamma = 90^\circ\).
(Axes unequal, angles 90°) - Hexagonal: \(a = b \neq c\); \(\alpha = \beta = 90^\circ, \gamma = 120^\circ\).
The system with axes of equal length (a=b=c) intersecting at 90-degree angles (\(\alpha=\beta=\gamma=90^\circ\)) is the Cubic crystal system.