Which statement is not true for metals?

• They form bcc structure

• They form hcp structure

• They form ccp structure

• They have low enthalpy of sublimation

How many crystal system are there when a≠b ≠c and a = b= c?

• 2,3

• 3,4

• 4,3

• 3,2

The cubic unit cell of a metal (molar mass = 63.55g mol^-1) has an edge length of 362 pm. Its density is 8.92 g cm^-3 . The type of unit cell is

• primitive

• face- centred

• body centred

• end centred

The flame colours of metal ions are due to

• Frenkel defect

• Schottky defect

• Metal deficiency defect

• Metal excess defect

Which one of the following statements about amorphous solids is incorrect?

• They melt over a range of temperature

• They are anisotropic

• There is no orderly arrangement of particles

• They are rigid and incompressible

If the distance between Na⁺ and Cl^- ionsin sodium chloride crystal is X pm, the length of the edge of the unit cell is

• 4X pm

• X/4 pm

• X/2 pm

• 2 X pm

Which of the following does not conduct electricity?

• Fused NaCl

• Solid NaCl

• Brine solution

• Copper

98.

Which one of the following defects in the crystals lowers its density?

• Frenkel defect

• Schottky defect

• F-centres

• Interstitial defect

The radii of Na⁺ and Cl^- ions are 95 pm and 181 pm respectively. The edge length of NaCl unit cell is :

• 276 pm

• 138 pm

• 552 pm

• 415 pm

Malleability and ductility of metals can be accounted due to

• the presence of electrostatic force

• the crystalline structure in metal

• the capacity of layers of metal ions to slide over the other

• the interaction of electrons with metal ions in the lattice