Problem 37
The general formula of an ionic compound crystallizing in zinc blende structure is (a) \(\mathrm{AB}_{3}\) (b) \(\mathrm{AB}_{2}\) (c) \(\mathrm{A}_{2} \mathrm{~B}_{2}\) (d) \(\mathrm{AB}\)
Problem 38
Which of the following statements is not correct? (a) The density of the crystal exhibiting Frenkel defect is less as compared to that of the perfect crystal (b) The Schottky defects are more common in ionic compounds with high coordination numbers and where the sizes of ions are small (c) In alkali halides, Frenkel defects are not found (d) The density of the crystal exhibiting Schottky defect is less as compared to that of the perfect crystal
Problem 39
Which of the following statements is not correct? (a) Heating of zinc oxide leads to the formation of a yellow coloured non- stoichiometric compound (b) The creation of cationic holes in ionic crystals imparts electrical conductivity to such crystals (c) The compound ferrous oxide can be prepared in its stoichiometric composition (d) Silver bromide shows both types of Schottky and Frenkel defects
Problem 40
On heating some polar crystals, weak electric current is produced. It is termed as (a) superconductivity (b) piezoelectricity (c) photoelectric current (d) none of these
Problem 41
Mark the correct statement (a) CsCl crystal show Schottky defect (b) Crystals having F-centres are coloured and paramagnetic (c) Photo sensitivity of AgBr is due to the presence of Frenkel defect in its crystals (d) all of these are correct
Problem 42
Which substance will conduct electric current in the solid state? (a) Diamond (b) Graphite (c) Sodium chloride (d) Iodine
Problem 43
The substance which possesses zero resistance at \(0 \mathrm{~K}\) is called (a) Super conductor (b) Insulator (c) Conductor (d) Semiconductor
Problem 44
In which of the following structures, the cation has maximum coordination number? (a) \(\mathrm{NaCl}\) (b) \(\mathrm{Na}_{2} \mathrm{O}\) (c) zinc blende (d) \(\mathrm{CaF}_{2}\)
Problem 45
In the zinc blende structure \((\mathrm{ZnS}), \mathrm{S}^{2}\) adopt ccp arrangement and \(\mathrm{Zn}^{2+}\) occupy (a) Alternate tetrahedral sites (b) Octahedral sites (c) Tetrahedral sites (d) Both octahedral and tetrahedral sites
Problem 46
An example of ferroelectric substance is (a) Tourmaline (b) Quartz (c) Barium titanate (d) Lead zirconate
