IMPORTANT QUESTIONS ON SOLID STATE

Q. NO	QUESTION
1	Why frenkel defect is not found in halides of alkali metals? (imp)
2	ZnO is white in color but turns yellow on heating. Why? (imp)
3	Why Crystal possessing CsCl structure change to NaCl structure on heating?
4	The ions of NaF and MgO have same number of electrons and internuclear distance are about the same (235 pm and 215 pm). Why are the melting point of NaF and MgO (992˚C and 2642˚C) so different?
5	Melting point of NaCl is greater than Na. Explain with reason.
6	Why the diffusion in solid is less than that in liquid?
7	Why the latent heat of fusion of CO2 is less than that of SiO2?
8	CsCl is more stable than NaCl. Explain
9	Addition of CdCl2 to a crystal of AgCl will produce schottky defect but not with NaCl. Why?
10	Gas lighter when pressed produces flame. Explain why?
11	Distinguish between crystal lattice and unit cell.
12	At what temperature range do most of metals become superconductors?
13	A compound is formed by two elements M and N. the element N forms ccp and atoms of M occupies 1/3 of tetrahedral voids. What is the formula of the compound? (imp)
14	Analysis shows that a metal oxide has empirical formula M0.96O1.00. Calculate the percentage of M2+ and M3+ ions in the sample.
15	Define forbidden zone in an insulator.
16	What type of alignments in crystals make them ferromagnetic?
17	(A)   AB crystallizes in a rock salt structure with A:B = 1:1. The shortest distance between A and B is y1/3 nm. The formula mass of AB is 6.022 Y amu where ‘Y’ is arbitrary constant. Find the density of AB in Kgm-3. (B)   If measured density is 20 Kgm-3. Identify the type of point defect.
18	The metal calcium crystallizes in face centered cubic unit cell with a = 0.556 nm. Calculate the density of metal if: (A)   It contains 0.2% frenkel defects. (B)   It contains 0.1% schottky defect.
19	Silicon is an insulator while silicon doped with phosphorus acts as a semiconductor. Why?
20	Some of the glass objects recovered from ancient monuments look milky instead of being transparent. Why?
21	Explain how the electrical conductivity of metal decreases with rise in temperature while that of a semiconductor increases?
22	Atoms of element B forms hcp lattice and those of element A occupy 2/3rd of tetrahedral voids. What is the formula of the compound formed by A and B? (imp)
23	What is Curie temperature?
24	Define unit cell.
25	Explain the nature of the crystal defect produced when sodium chloride crystal is doped with MgCl2.
26	What is the radius ratio for an ion to occupy octahedral void?
27	The radii of P+ and Q- are 0.95 Å and 1.81 Å respectively. Predict whether its coordination number of PQ is 6 or 4.
28	What are 12-16 and 13-15 compounds? (imp)
29	Give one example of silicate with chain structure.
30	What are pyrosilicates? Give example.