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Chemistry Question on sulphur

Monoclinic crystal has dimension

A

a=b=c; α\alpha≠β\beta≠γ\gamma≠900

B

a=b≠c; α\alpha=β\beta=γ\gamma=900

C

a=b=c; α\alpha=β\beta=γ\gamma=900

D

a≠b≠c; α\alpha=γ\gamma= 900; β\beta≠ 900

Answer

a≠b≠c; α\alpha=γ\gamma= 900; β\beta≠ 900

Explanation

Solution

Monoclinic crystal has dimension:a≠b≠c; α\alpha= γ\gamma= 90 0; β\beta≠ 90 0

For monoclinic crystals,axial lengths are not equal. Hence **** a≠b≠c and the axial angles α\alpha = γ\gamma= 90 0; β\beta≠ 90 0

The monoclinic crystal system is one of the practical crystal systems in crystallography. Three vectors are used to describe the crystal system. For example, quartz is described by vectors of inequitable lengths forming a rectangular typeprismwith a parallelogram base. Some of the common characteristics of the monoclinic crystals are:

  • Orientation of a crystal has few constraints – where b is the only fixed axis by symmetry.
  • Axis C is generally chosen based on cleavage and habit.
  • α and γ = 90 0
  • In some cases, the b axis will be 90 0(pseudo-orthorhombic form)
  • Symmetry operation in a monoclinic system, theunprecedented operation is 2/m – a twofold axis of rotation with a mirror plane.
  • The axis b is the rotation, whilec and a lie in the mirror plane.
  • Monoclinic crystals have two forms : pinacoids and Monoclinic shape crystals have two shapes: pinacoidal and prisms.
  • Common monoclinic rock-forming crystals include clinopyroxene, orthoclase, mica, and titanite.

Also Read:Amorphous and Crystalline Solids