Gus Paper

Guess Paper – 2009
Class – XII
Subject –Chemistry : Solid State

(Q.1) The appearance of colour in solid alkali metal halides is generally due to: ( 1 mark )
(a) Frenkel defect(b) Interstitial positions(c) F-centres(d) Schottky effect

(Q.2) Schottky defects in crystal is observed when ( 1 mark )

(a) unequal number of cations and anions aremissing from the lattice(b) equal number of cations and anions are missing from the lattice(c) an ion leaves its normal siteand occupies an interstitial site(d) density of the crystal is increased

(Q.3) In an antiflourite structure, cations occupy: ( 1 mark )
(a) Octahedral voids(b) Centre of the cube(c) Tetrahedral voids(d) Corners of the cube

(Q.4) A p-typesemiconductor is electrically ( 1 mark )
(a) Negative(b) Positive(c) Neutral(d) Depends upon the concentration of impurities

(Q.5) Ferrimagnetism is shown by ( 1 mark )
(a) Nickel(b) Oxygen molecule(c) Cromium oxide (CrO2)(d) Magnetite

(Q.6) What are the stoichiometric defects found in ionic crystals? ( 1 mark )

(Q.7) Write two examples of amorphous solids? ( 1 mark )

(Q.8) A solid substance XY has a rock salt geometry. What is the co-ordination number of X and Y? How many atoms of X and Y are present in the unit cell? ( 1 mark )

(Q.9) What type of solids are malleable, ductile and electrical conductors? ( 1 mark )

(Q.10) How many atoms are present in the unit cell of bcc and fcc? ( 1 mark )

(Q.11) Sometimes,common salt is yellow instead of being pure white. Why? ( 1 mark )

(Q.12) What are voids?
( 1 mark )

(Q.13) What happens when ferrimagnetic Fe3O4 is heated to 850 K?
( 1 mark )

(Q.14) Name thepoint defect which lowers the density of a crystal.
( 1 mark )

(Q.15) What is the co-ordination number of Na+ and Cl- ions in NaCl structure? ( 1 mark )

(Q.16) What do you mean by F-center?
( 1 mark )

(Q.17) Name the type of solids which have long range orders.
( 1 mark )

(Q.18) Name one solid which has both Frenkel