What is meant by anisotropy? Which of the two : quartz or glass shows this property?

Define the following terms:
(i) ferromagnetism
(ii) Ferrimagnetism

Define the following:
(i) Dislocation
(ii) F-centre
(iii) Anti-ferroelectric

What type of structure is generally adopted by alkali metal halides at ordinary temperature and pressure? What happens to structure when pressure is applied to alkali metal halides?

What are point defects in crystals and how do they develop?

What do you understand by non-stoichiometric compounds? Give examples.

Ionic solids which have anionic vacancies to metal excess defect develop colour. Explain with the help of a suitable example.

Examine the given defective crystal

Answer the following questions:
(i) What type of stoichiometric defect is shown by the crystal?
(ii) How is the density of the crystal affected by this defect?
(iii) What type of ionic substances show such defect?

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.
(ill) 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?