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Crystal System and Bravais Lattice

If all the th...

Question

If all the three inter-axial angles defining the unit cell are equal in magnitude, the crystal cannot belong to the ______ system.

A

Orthorhombic

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B

Hexagonal

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C

Tetragonal

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D

Cubic

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Solution

The correct option is B Hexagonal

Let the inter axial angles be $α, β, γ$

In hexagonal unit cell $α = β \neq γ$ .
$I n c a s e o f h e x a g o n a l s y s t e m$
$α = β = 90^{o} a n d δ = 12 0^{o} (a x i a l a n g l e)$
$I n c a s e o f a l l o t h e r s y s t e m$
$α = β = δ = 90^{o}$
$H e n c e c o r r e c t o p t i o n i s h e x a g o n a l$

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