The most efficient packing is present in -

1. HCP and BCC

2. HCP and CCP

3. BCC and CCP

4. BCC and Simple cubic cell

Subtopic:  Density & Packing Fraction |
 82%
From NCERT
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The percentage of empty space in a body centred cubic arrangement is ......... .

1.  74

2.  68

3.  32

4.  26

 

Subtopic:  Density & Packing Fraction |
 83%
From NCERT
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The incorrect statement among the following regarding hexagonal close packing is:

1. The coordination number is 12.
2. It has 74% packing efficiency.
3. Tetrahedral voids of the second layer are covered by the spheres of the third layer.
4. In this arrangement, spheres of the fourth layer are exactly aligned with those of the first layer.

Subtopic:  Density & Packing Fraction |
 61%
From NCERT
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Same coordination number for cations and anions is present in:

1. Cl- ions form Fcc lattice and Na+ ions occupy all octahedral voids of the unit cell.
2. Ca2+ ions form Fcc lattice and F- ions occupy all the eight tetrahedral voids of the unit cell.
3. O2- ions form Fcc lattice and Na+ ions occupy all the eight tetrahedral voids of the unit cell.
4. S2- ions form Fcc lattice and K+ ions go into alternate tetrahedral voids of the unit cell.
Subtopic:  Voids, Radius Ratio & Coordination Number |
 78%
From NCERT
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The coordination number of a square close-packed structure in two dimensions is -

1. 2

2. 3

3. 4

4. 6

Subtopic:  Introduction & Crystal System |
 76%
From NCERT
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Doping causes-

1. Dislocation defect.

2. Schottky defect.

3. Frenkel defect.

4. Electronic defect.

Subtopic:  Imperfections in Solids & Semiconductors |
 70%
From NCERT
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Silicon doped with electron rich impurity forms -

1. p-type semiconductor.

2. n-type semiconductor.

3. Intrinsic semiconductor.

4. Insulator.

Subtopic:  Imperfections in Solids & Semiconductors |
 83%
From NCERT
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The incorrect statement among the following is:

1. Paramagnetic substances are weakly attracted by magnetic field.
2. Ferromagnetic substances cannot be magnetised permanently.
3. The domains in antiferromagnetic substances are oppositely oriented with respect to each other.
4. Pairing of electrons cancels their magnetic moment in the diamagnetic substances.

Subtopic:  Magnetic Behaviour of an Element/Compound |
 77%
From NCERT
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Which of the following is not true about the ionic solids?

1. Bigger ions form the close packed structure
2. Smaller ions occupy either the tetrahedral or‘the octahedral voids depending upon their size
3. Occupation of all the voids is not necessary
4. The fraction of octahedral or tetrahedral voids occupied depends upon the radii of the ions occupying the voids

Subtopic:  Voids, Radius Ratio & Coordination Number |
From NCERT
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A ferromagnetic substance becomes a permanent magnet when it is placed in a magnetic field because:

1. All the domains get oriented in the direction of the magnetic field.
2. All the domains get oriented in the direction opposite to the direction of the magnetic field.
3. Domains get oriented randomly.
4. Domains are not affected by the magnetic field.

Subtopic:  Magnetic Behaviour of an Element/Compound |
 80%
From NCERT
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