Crystals can be classified into :

• 7 systems
• 9 systems
• 10 systems

Axis of symmetry are called "Hexad"

• If original appearance is repeated twice
• If original appearance is repeated 6 times
• If original appearance is repeated after an angle of 90.

Radius ratio rNa+/rCl- in NaCl crystal is :

• 0.524
• 0.414
• 0.732
• 0.80

Which one of the crystal has the highest melting point ?

• Ionic crystal
• Covalent crystal
• Metallic crystal
• Molecular crystal

Axis of symmetry in crystals is given by the general formula:

• 360/n
• n X 360
• n X 180
• non

If a plane is parallel to an axis of crystal its Miller index will be :

• zero
• infinity
• one
• none

21. If in a crystal intercepts are l, oo and, oo the Miller indices are :

• (1 0 0)
• (1 0 1)
• (1 1 0)
• (0 0 0)

Crystals can be classified into

• 7 systems
• 9 systems
• 10 systems

In Braggs equation for diffraction of X-rays , n represents :

• no. of moles
• quantum no
• order of reflection
• Avogadro no.

In a body centred cubic arrangement A ion occupies the centre while B ions occupy corners of cubic, the formula of solid is :

• A2B
• AB
• AB2
• none of these

Closest packing is maximum in the crystal lattice of:

• face centred cubic
• bcc
• simple centred cubic

Axis of symmetry are called Hexad

• If original appearance is repeated twice
• If original appearance is repeated 6 times
• If original appearance is repeated after an angle of 90 degree

Braggs equation is :

• (2dnlambda =sin { heta } )
• (nlambda =2dsin { heta } )
• (nlambda =dsin { heta } )

The no. of atoms per unit cell in simple cubic, face centred cubic and body centred cubic are:

• 1, 4, 2
• 4, 1, 2
• 2, 4,1
• 4, 8, 2

Total no. of planes, axes and centre of symmetries in a crystal is termed as:

• elements of symmetry
• symmetries
• symmetry operations

In a unit cell of NaCl lattice there are :

• 4 NaCl units
• 3 Na⁺ ions
• 6 Na⁺ ions
• 6 Cl^- ions

KCI is a....... conductor of electricity:

• good
• bad
• semi
• non

Name of equation related to X-ray diffraction by crystals is:

• Law equation
• Braggs equation
• Lewis equation

Coordination no. for an atom in a primitive cubic unit cell is :

• 6
• 8
• 10
• 12

The geometrical form consisting only of a regular array pf points in space is called:

• unit cell
• lattice
• crystal
• amorphous solid