The property of crystalline solid is not

Wax is an example of

In a tetragonal crystal

An example of a face centered cubic lattice is

The number of octahedral sites per sphere in fcc structure is

Which is not the correct statement for ionic solids in which positive and negative ions are held by strong electrostatic attractive forces ?

In crystal structure of NaCl, total number of Cl^- ions in a unit cell is

Which of the following FCC structure contains cations in alternate tetrahedral voids ?

The fraction of the total volume occupied by the atoms present in a simple cube is

A compound M_pX_q has cubic close packing(ccp) arrangement of X.Its unit cell structure is shown below.The empirical formula of the compound is

Write a point of distinction between a metallic solid and an ionic solid other than metallic lustre.

What is meant by an 'intrinsic semiconductor'?

Give an example of an ionic compound which shows Frenkel defect.

A group 14 element is to be converted into n-type semiconductor by doping it with suitable impurity. To which group should this impurity belong?

What type of crystalline solid is graphite?

Classify the following substances into ionic, covalent, molecular or metallic:
MgO, SO₂,I₂,H₂O (ice), SiO₂ (quartz), brass.

Arrange the following according to their packing fractions:
Simple cubic, face-centred cubic, body-centred cubic.

What is meant by point defect in crystals?

Calculate the packing efficiency in case of a metal crystal for simple cubic lattice.

Explain each of the following with a suitable example:
(i) Paramagnetiwsm
(ii) Frenkel defect in crystals.

Certain crystals, when subjected to a mechanical stress get deformed and produce electricity due to displacement of ions. The electricity thus produced is called piezoelectricity and such crystals are called piezoelectric crystals. On the other hand, when such crystals are subjected to an electric field, the atomic displacements are produced which cause mechanical distortion in the crystals. These unique properties of piezoelectric crystals find several applications. Now, answer the following questions:
(i) How do piezoelectric crystals behave?
(ii) Mention one application of piezoelectric crystals.
(iii) Just like certain crystals piezoelectric crystals perform better even under mechanical stress and show' various application, how do you behave under stress? What values we can adopt from even these non-living crystals?

Compounds having general molecular formula  \(AFe_{ 2 }O_{ 4 }\) are called ferrites and posses spinel type structures. Some common examples are \(MgFe_{ 2 }O_{ 4 }\)  and \(ZnFe_{ 2 }O_{ 4 }\) They may be thought of being formed by replacing \(Fe^{ 2+ }\) ions present in \(Fe_{ 3 }O_{ 4 }\) by bivalent cations such as \(Mg^{ 2+ },Zn^{ 2+ }\) ions etc. Now answer the following questions :
(i) What types of materials are ferrites?
(ii) What are the main uses of ferrites?