Test: MCQs (One or More Correct Option): The Solid State & Surface Chemistry | JEE Advanced - JEE MCQ

The crystals of CsCl has body - centred cubic unit cell. Hence, each ion in this structure has coordination number of eight.

NOTE : In case of crystals of NaCl two
interpenetrating face-centred cubic lattices are
present, one of these is composed entirely of Na⁺ ions and the other of Cl^– ions. Each Na⁺ ion is located half way between two Cl^– ions and viceversa. A unit cell of NaCl crystal has Cl^– ions at the corners as well as at the face centres and Na⁺ ions are located in
octahedral voids. On each edge of cubic unit cell, there are two Cl^– ions and one Na⁺ ions. Hence

(b,c)
Frenkel defect is a dislocation effect, observed when the size of the cation and anion differ largely. F-center is created when an anion is lost from the lattice and vacancy is filled by trapping of an electron. Schottky defect changes the density of a crystalline solid.

(a, b, d)
(a) ΔH is negative for adsorption
(b) Fact based
(d) Chemical bonds are stronger than vander Waal’s forces, so chemical adsorption is more exothermic

(a, c)
Graph (I) and (III) represent physisorption because, in
physisorption, the amount of adsorption decreases with the increase of temperature and increases with
the increase of pressure.
Graph (II) represent chemisorption, because in chemisorption amount of adsorption increases with the
increase of temperature. Graph (IV) is showing the formation of a chemical bond, hence chemisorption.

In ccp, O2– ions are 4.
Hence total negative charge = –8
Let Al3+ ions be x, and Mg2+ ions be y.
Total positive charge = 3x + 2y
⇒ 3x + 2y = 8
This relation is satisfied only by x = 2 and y = 1.
Hence number of Al³⁺ = 2.
and number of Mg²⁺ = 1.
⇒ n = fraction of octahedral holes occupied by Al³⁺

and m = fraction of tetrahedral holes occupied by Mg²⁺

Reaction on metal surface

This is an example of chemisorption

CCP is ABC ABC …… type packing
(A) In topmost layer, each atom is in contact with 6 atoms in same layer and 3 atoms below this layer

(B) Packing fraction = 

(C) Each FCC unit has effective no of atoms = 4
Octahedral void = 4
Tetrahedral void = 8
(D) 4r = a√2