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TN 12th Computer Applications மின்னணு செலுத்தல் முறைகள் Sample Question Papers Study Material - QB365 Set A

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TN 12th Computer Applications மின் - வணிகம் Sample Question Papers Study Material - QB365 Set A

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12th Standard English Medium Chemistry Subject Solid State Book Back 2 Mark Questions with Solution Part - I

Published on: 01/06/2021

QB365 provides detailed and simple solution for every Book back Questions in class 12 Chemistry Subject. It will helps to get more idea about question pattern in every book back questions with solution.

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Std: 12th Standard - Chemistry

chapter: - Book back Questions

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Questions:

Generic 3

3 x 3 = 9

Distinguish tetrahedral and octahedral voids.

Distinguish between hexagonal close packing and cubic close packing.

Explain briefly seven types of unit cell.

Generic 2

1 x 2 = 2

What are point defects?

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Answers Key:

Generic 3

3 x 3 = 9

Tetrahedral voids Octahedral voids. 1. A void surrounded by 4 spheres occupying the corners of a tetrahedron. A void surrounded by 6 spheres along the corners of an Octahedron 2. It is formed when a sphere of second layer placed above the void of first layer. All the voids of first row which remain unoccupied from octahedral. 3. Co-ordination number is 4. Co-ordination number is 6. 4. The number of tetrahedral voids are equal to 2n. The number of Octahedral voids are equal to n.

	hcp structure	ccp structure
1.	This is 'aba' pattern of arrangement.	This is 'abc' pattern of arrangement.
2.	The spheres can be arranged so as to fit into the depression in such a way that the third layer is directly over a first layer.	The third layer may be placed over the second layer in such a way that all the spheres of the third layer fit in octahedral voids.
3.	The tetrahedral voids of the second layer are covered by the spheres of the third layer.	This arrangement of the third layer is different from other two layers and the stacking of layers continued.
4.	6 spheres are present	4 spheres are present

There are seven types of unit cell, Cubic, tetragonal, orthorhombic, hexagonal, monoclinic, triclinic and rhombohedral. They differ in the arrangement of their crystallographic axes and angles.
i) Cubic: a = b = c; α = β = ૪ = 90^o.

ii) Tetragonal: a = b ≠ c; α = β = ૪ = 90°.

iii) Orthorhombic: a ≠ b ≠ c; α = β = ૪ = 90°.

iv) Hexagonal: a = b ≠ c; α = β = 90^o, ૪ = 120^o.

v) Monoclinic: a ≠ b ≠ c; α = ૪ = 90^o, β ≠ 90^o,

vi) Triclinic: a ≠ b ≠ c; α ≠ β ≠ ૪ ≠ 90^o.

vii) Rhombohedral: a = b = c; α = β = ૪ ≠ 90^o.

Generic 2

1 x 2 = 2

The imperfection occurs due to missing atoms, displaced atoms or extra atoms, is named as a point defect. Such defects arise due to imperfect packing during the original crystallisation or they may arise from thermal vibrations of atoms at elevated temperatures.