2 Tetragonal: \(a=b \neq c ; \quad \alpha=\beta=\gamma=90^{\circ}\)
3 Orthorhombic: \(a \neq b \neq c ; \quad \alpha=\beta=\gamma=90^{\circ}\)
4 Rhombohedral: \(a=b \neq c ; \quad \alpha=\beta=\gamma=90^{\circ}\)
Explanation:
For Rhombohedral, \(a=b=c, \alpha=\beta=\gamma \neq 90^{\circ}\)
CHXII01:THE SOLID STATE
318789
I. Possible variations for a cubic crystal system is primitive only. II. The axial angles of a hexagonal crystal system are \(\alpha=\beta=90^{\circ}\) and \(\gamma=120^{\circ}\). Which of the above statement(s) is/are true?
1 Only I
2 Only II
3 Both I and II
4 None of these
Explanation:
For a cubic crystal system, the possible variations are primitive, body-centred and facecentred. The axial angles of a hexagonal crystal system are \(\alpha=\beta=90^{\circ}\) and \(\gamma=120^{\circ}\).
2 Tetragonal: \(a=b \neq c ; \quad \alpha=\beta=\gamma=90^{\circ}\)
3 Orthorhombic: \(a \neq b \neq c ; \quad \alpha=\beta=\gamma=90^{\circ}\)
4 Rhombohedral: \(a=b \neq c ; \quad \alpha=\beta=\gamma=90^{\circ}\)
Explanation:
For Rhombohedral, \(a=b=c, \alpha=\beta=\gamma \neq 90^{\circ}\)
CHXII01:THE SOLID STATE
318789
I. Possible variations for a cubic crystal system is primitive only. II. The axial angles of a hexagonal crystal system are \(\alpha=\beta=90^{\circ}\) and \(\gamma=120^{\circ}\). Which of the above statement(s) is/are true?
1 Only I
2 Only II
3 Both I and II
4 None of these
Explanation:
For a cubic crystal system, the possible variations are primitive, body-centred and facecentred. The axial angles of a hexagonal crystal system are \(\alpha=\beta=90^{\circ}\) and \(\gamma=120^{\circ}\).