Question
Copper has the face centred cubic structure. The coordination number of each ion is:
-
4
-
12
-
14
-
8
Solution
A.
4
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Copper has the face centred cubic structure. The coordination number of each ion is:
4
12
14
8
A.
4
Sponsor Area
(i) What is Schottky defect in a solid?
(ii) A bcc element (atomic mass 65) has a cell edge of 420 pm. Calculate its density in gms / cm3.
i) When in a crystal lattice cations and anions both are missing from their normal site leaving holes then the defect is known as Schottky defect. For example KBr, NaCl, KCl.
ii) We have given,
Z = 2
cell edge = 420 pm
NA = 6.023 x 1023
Mass = 65 g
density = ? 
i) What are F-centres in an ionic crystal?
(ii) Why are crystals having F-centres paramagnetic?
(i) Ionic compounds having non-stoichiometric defects, anionic vacancies are occupied by electrons. These are known as F-centres. These electrons are delocalised and responsible for importing colours to crystals.
(ii) Free impaired electrons occupying anionic vacancies spin in a particular direction result in the magnetic moment and ionic crystals with F-centres. So, they show paramagnetic behaviour.
For a crystal of diamond, state:
(i) The hybridisation of the carbon atom.
(ii) The coordination number of each carbon atom.
(iii) The type of lattice in which it crystalises.
(iv) The number of carbon atoms present per unit cell.
(i) Sp3 hybridization
(ii) Coordination number = 4
(iii) Lattice type = Giant network type with fcc arrangement of c-atoms.
(iv) Number of particles per unit cell = 4
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