Question

1. Interatomic bonds in ceramics are a. covalent and ionic b. ionic and van der Waals c. covalent and van der Waals d. covalent and metallic 2. In metallic bonding, a electrons are tightly attached to nuclei b. free electrons act as a glue holding the ion cores together c. interatomic bonds are non-directional d. b and c Number of valence electrons in Mn (atomic number of 25) is equal to a. 6 b. 7 c. 14 d. 2 ne coordination number of atoms in the hexagonal close-packed (HCP) crystal structure * 5. a. 8 b. 12 c. 4 d. 6 The number of atoms in the unit cell of the simple cubic (SC) crystal structure is a. 1 b. 2 c. 8 d. 4

Answer 1

1)ceramiics consists of 2 or more elements. These atoms are
connected by covalent and ionic bonds
Answer :: option A;; covalent and ionic
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2)
Metals show metallic boning.where electrons move freely and
it will hold ion cores. SInce free electrons are every where
and it is attracted by nuclei,the bonding is non directional
like ionic bond

Hence answer
option D: b and c
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3)
Mn electron configuration is ::[Ar] 3d5 4s2
4 th shell is valance shell,it has 2 electrons

Hence answer
option d:2
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For a unit cell ,number of atoms touching a particular atom is
called coordination number .For hexagonal close packing there are
12 electron around an atom. thus its coordination number is 12

option B:: 12
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In simple cubic unit cell atoms present in each corners
of the cube. Thus there are 8 atoms present in a SC

option C:: 8
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