Guess Paper: CBSE Class XII Chemistry - 2013 (Chapter-wise)

CBSE Class X  English

Important Questions

Solid State

1. Mention the characteristic properties of solid.
Mention the differences between crystalline solid and amorphous solid.
Explain the terms a) anisotropy b) isotropy. Why is crystalline solid anisotropic while amorphous solid isotropic in nature? 
What makes glass different from quartz? Under what condition quartz is converted to glass?
Why are amorphous solids called pseudo solids or super cooled liquids?
How are crystalline solids classified on the basis of intermolecular forces? Give two examples of each type  and mention  their properties.
Compare the properties of diamond and graphite on the basis of their structures.
Classify the following as ionic, metallic, molecular, covalent, or amorphous.

a) P4O10

9. How are molecular solids subdivided further? Give two examples each and mention their properties.
Account for the following:

a) Glass panes fixed to windows of old buildings becomes slightly thicker at the bottom than at the top.
b) NaCl(s) does not conduct electricity but it conducts either in molten state or in aqueous solution.
c) Diamond is a non conductor while graphite is a conductor of electricity.
d) Diamond is hard while graphite is soft.
e) Graphite is a lubricant.
f) Ionic solids are hard and brittle.
g) MgO and NaCl are ionic solids but MgO has higher melting point than NaCl.
h) NaCl exhibit schottky defect and not frenkel defect.

11. Explain the terms

a) lattice point
b) crystal lattice
c) unit cell.

12. What are Bravis lattices? Mention the characteristics of a crystal lattice.
Mention the characteristics of a unit cell. Draw a neat diagram of a unit cell and show its parameters.
What is the difference between primitive and centered unit cell?
Calculate the number of atoms in

a) SCC
b) BCC
c) FCC unit cells.

16. Mention the characteristics of seven primitive unit cells and their possible variation as centered unit cells.
Name the centered unit cells and position of atoms in each centered unit cell.
What do you mean by coordination number? Give the coordination number of atoms in

a) one dimensional arrangement of atoms
b) square close packing in two dimension.
c) hexagonal close packing in two dimension
c) hexagonal close packing in three dimension
d) cubic close packing or fcc in three dimension
e) cation in triangular void.
f) cation in tetrahedral void 
g) cation in cubic void
h) bcc

19. A compound has hexagonal close packing structure. Determine the total number of  voids, number of tetrahedral void, and number of octahedral voids in 0.5 mole of this compounds.
Calculate the number of octahedral and tetrahedral voids in unit cells of a)SCC   b)BCC c)FCC
Distinguish between

a) octahedral and tetrahedral voids
b) Schottky and Frenkel defect.
c) Hexagonal closed packing and cubic close packing
d) crystal lattice and unit cell.
e) para magnetism and ferro magnetism
f) hexagonal and monoclinic unit cell
g) face centered and end centered unit cell.

22. Calculate the % efficiency of packing in

a) SCC
b) BCC
c) FCC

23. If the radius of octahedral void is r and the radius of atoms in close packing is R, derive the relationship between r and R.

24. What are interstitial defects? Mention its effect on density of a solid.

25. What is the effect of adding

a) SrCl2 to NaCl
b) CdCl2 to AgCl?

26. Explain the terms with suitable examples

a) Stoichiometric and non stoichiometric defects
b) F centre
c) Metal deficiency defect
d) 12-16 and 13-15 compounds
e) paramagnetism
f) diamagnetism 
g) ferromagnetism
h) ferrimagnetism
i) antiferromagnetism

27. What happens when

a) NaCl crystal is heated with Na vapors
b) ZnO is heated
c) Fe3O4 is heated.

28. Explain n type and p type conduction with suitable examples.

29. Classify the following as n type or p type semi conductors.

a) Ge doped with In
b) B doped with Si.

30. In terms of band theory explain the differences between conductor , insulator, and semi conductor. Draw a neat diagram to show the valence band and conduction band in conductor,  insulator and semi conductor.

Numerical Questions

31. Derive the expression for determining the density of unit cell.

1. Iron(II) oxide crystallize as Fe 0.93O. Find the %Fe2+  and Fe3+ in this compound
A Solid AB has NaCl structure. If the radius of cation A+ is 100 pm, what is the possible maximum and minimum radius of anion B-
If the radius of Mg2+, Cs+, O2-,S2- and Cl- ion are 0.65 A0, 1.69 A0, 1.40 A0, 1.84 A0 and 1.81 A0 respectively. Find the coordination number of MgO,MgS and CsCl.
In corundum, oxide ion are in hcp and aluminium ion occupy 2/3 of the octahedral void. What is the formula of aluminium oxide?
A cubic solid is made up of two elements P and Q. Q occupies corners of the cube and P occupies the body centre. What is the formula of the compound?
  In a crystalline solid anion C occupies ccp, cation A occupies 50% tetrahedral void and cation B occupies 50% octahedral void. What is the formula of the compound?
If NaCl is doped with 10-3 mole % SrCl2 . What is the concentration of cation  vacancies?
Sodium metal crystallizes in bcc with a cell edge of 4.3 A0. What is the radius of sodium atom?
Copper crystallizes in fcc with a density 9g/cm3.Calculate the radius of copper atom (Atomic mass of Cu=63)
Cr crystallizes in bcc with atomic diameter 250pm. Determine the density of unit cell. (Atomic mass of Cr=52)
Calculate the value of Avagadro number. Given Density of unit cell of NaCl=2.165  g/cm3 Distance between Na+ and Cl- is 281pm. Atomic mass of NaCl= 58.5.
CsBr has bcc structure.a= 400pm Calculate the distance between Cs+ and Br-
KF has NaCl structure. Find the distance between K+ and F-. Density of unit cell= 2.5 g/ cm3 ( Molar mass of KF = 58 )
An element crystallizes in bcc. a = 288 pm. How many atoms are there in 208 grams of this elements?
An element crystallizes in fcc with a = 200 pm. Calulate its density if 200grams of this element contains 24x 1023 atoms.
Unit cell of an element has atomic mass 108. d= 10.5 g/cm3 a= 409 pm. Find the structure of the crystal lattice.
A compound has hexagonal close packing structure. Determine the total number of voids, number of  tetrahedral void, and number of octahedral voids in 0.5 mole of this compounds.
18. Al crystallizes in a cubic close packing structure.  Its metallic radius is 125 pm .Find the edge length of the unit cell. How many unit cells are there in 1cm3 of Al ? How many atoms are there in 1cm3 of Al ?
  Silver chrysalises in FCC with an edge length 409 pm and density 10.5g/cm3. Calculate the Atomic mass of silver.

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