Which of the following compounds is metallic and ferromagnetic?

• VO₂

• MnO₂

• TiO₂

• TiO₂

Sodium metal crystallises in a body centred cubic lattice with a unit cell edge of 4.29 Å The radius of sodium atom is approximate:

• 1.86 Å

• 3.22Å

• 5.72 Å

• 5.72 Å

CsCl crystallises in body centred cubic lattice. If 'a' its edge length, then which of the following expression is correct?

Lithium forms body centred cubic structure. The length of the side of its unit cell is 351 pm. Atomic radius of the lithium will be

• 75 pm

• 300 pm

• 240 pm

• 240 pm

In a face centred cubic lattice, atom A occupies the corner positions and atom B occupies the face centre positions. If one atom of B is missing from one of the face centred points, the formula of the compound is:

• A₂B 

• AB₂

• A₂B₃

• A₂B₃

The edge length of a face centred cubic cell of an ionic substance is 508 pm. If the radius of the cation is 110 pm, the radius of the anion is 

• 144 pm

• 288 pm

• 398 pm

• 398 pm

Percentages of free space in cubic close packed structure and in body centred packed structure are respectively

• 48% and 26%

• 30% and 26%

• 26% and 32%

• 26% and 32%

8.

A metal crystallises in a face centred cubic structure. If the edge length of its unit cell is'a', the closest approach between two atoms in metallic crystal will be

• 2a

• 
• 
• 

Copper crystallizes in fcc with a unit cell length of 361 pm. What is the radius of copper atom?

• 108 pm

• 127 pm

• 157 pm

• 157 pm

In a compound atoms of element Y from ccp lattice and those of element X occupy 2/3rd of tetrahedral voids. The formula of the compound will be 

• X₄Y₃

• X₂Y₃

• X₂Y

• X₂Y