|2007 Set-1 Delhi
Q. What is the number of atoms per unit cell in a body-centred cubic structure?
Q. Explain each of the following with a suitable example: (i) Paramagnetism(ii) Piezoelectric effect(iii) Frenkel defect in crystals
Q. What is the coordination number of each type of ions in a rock-salt type crystal structure?
2008 Set-2 Delhi
Q. What is the total number of atoms per unit cell in a face-centred cubic (fcc) structure?
Q. What type of substances exhibits antiferromagnetism?
Q.How would you account for the following? (i) Frenkel defects are not found in alkali metal halides.(ii) Schottky defects lower the density of related solids.(iii) Impurity doped silicon is a semiconductor.
Q.Explain the following properties giving suitable examples: (i) Ferromagnetism(ii) Paramagnetism(iii) Ferrimagnetism
2009 Set-1 Delhi
Q.Which point defect in crystals does not affect the density of the relevant solid?
Q.Iron has a body-centred cubic unit cell with a cell edge of 286.65 pm. The density of iron is 7.87 g cm. Use this information to calculate Avogadro’s number.
2010 Set-3 Delhi
Q.Which point defect in crystals of a solid decreases the density of the solid?
Q.The density of copper metal is 8.95 g cm. If the radius of copper atom is 127.8 pm, is the copper unit cell a simple cubic, a body-centred cubic or a face centred cubic structure? (Given: At. Mass of Cu = 63.54 g mol and NA = 6.02 × 1023 mol)
2011 Set-1 Delhi
Q.‘Crystalline solids are anisotropic in nature’. What does this statement mean?
Q.Silver crystallizes in face-centred cubic unit cell. Each side of this unit cell has a length of 400 pm. Calculate the radius of the silver atom. (Assume the atoms just touch each other on the diagonal across the face of the unit cell. That is each face atom is touching the four corner atoms.)
2012 Set-1 Delhi
Q. What is meant by doping in a semi-conductor?
Q. Tungsten crystallizes in body centered cubic unit cell. If the edge of the unit cell is 316.5 pm, what is the radius of tungsten atom?