Q.1.
If
three elements X, Y and Z crystallize in a cubic solid with X atoms at the
corners, Y atoms at the cube centres and Z atoms at the faces of the cube, then
write the formula of the compound.
Q.2. In a solid ‘AB’, ‘A’ atoms have ccp arrangement and B atoms occupy all the octahedral sites. If all the face centred atoms along one of the axes are removed, then what will be the resultant stoichiometry of the compound?
Q.3. What is the difference between glass and quartz while both are made up from SiO4 tetrahedral? Under what conditions could quartz be converted in to glass?
Q.4. What difference in behaviour between the glass and sodium chloride would you expect to observe if you break off a piece of either cube?
Q.5. KF has ccp structure. Calculate the radius of the unit cell if the side of the cube or edge length is 400 pm. How many F– ions and octahedral voids are there in the unit cell?
Q.6. How will you show that glass is a supercooled liquid?
Q.7. What is the two-dimensional coordination number of a molecule in square packed layer?
Q.8. Solid A is very hard electrical insulator in solid as well as in molten state and melts at extremely high temperature. What type of solid is it?
Q.9. How many octahedral voids are there in 1 mole of a compound having cubic closed packed structure?
Q.10. Both diamond and rhombic sulphur are covalent solids but the latter has very low melting point than the former. Explain why?
Q.11. Write a feature which will distinguish a metallic solid from an ionic solid.
Q.12. What is the total number of atoms per unit cell in a face centred cubic structure?
Q.13. Some of the very old glass objects appear slightly milky instead of being transparent. Why?
Q.14. An ionic compound AB2 possesses CaF2 type crystal structure. Write the co–ordination numbers of A2+ and B– ions in crystals of AB2.
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