Which of the following statements is correct about the conduction of electricity in pure crystal of silicon atroom temperature?

(1) The conduction is due to electrons present in fully occupied lowest energy states.

(2) The conduction is due to only some electrons capable of leaving the bonds at room temperature.

(3) The conduction is only due to the holes formed from the release of electrons.

(4) The conduction is due to the movement of both the electrons released and holes formed.

Subtopic:  Density & Packing Fraction |
 56%
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Hints

Calculate the Miller indices of crystal planes which cut through the crystal axes at (i) (2a, 3b, c), (ii) (∞, 2b, c )

(1) 3, 2, 6 and 0, 1, 2

(2) 4, 2, 6 and 0, 2, 1

(3) 6, 2, 3 and 0, 0, 1

(4) 7, 2, 3 and 1, 1, 1

Subtopic:  Introduction & Crystal System |
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NEET 2023 - Target Batch - Aryan Raj Singh
Hints

Caculate the distance between 111 planes in a crystal of Ca. Repeat the calculation for the 222 planes. (a = 0.556nm)

(1) 016.1 nm

(2) 0.161 nm

(3) 0.610 nm

(4) None of the above

Subtopic:  Density & Packing Fraction |
 62%
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A metallic element crystallizes into a lattice containing a sequence of layers of ABABAB ............ Any packing of spheres leaves out voids in the lattice. The percentage by volume of empty space of this is

(1) 26%

(2) 21%

(3) 18%

(4) 16 %

Subtopic:  Introduction & Crystal System |
 86%
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Silver metal crystallises in a cubic closest – packed arrangement with the edge of the unit cell having a length a = 407 pm. What is the radius of silver atom.

(1) 143.9 pm

(2) 15.6 pm

(3) 11.59 pm

(4) 13.61 pm

Subtopic:  Introduction & Crystal System | Density & Packing Fraction |
 79%
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From the fact that the length of the side of a unit cell of lithium is 351 pm. Calculate its

atomic radius. Lithium forms body-centered cubic crystals.

(1) 152.69 pm

(2) 62.71 pm

(3) 151.98 pm

(4) 54.61 pm

Subtopic:  Introduction & Crystal System |
 76%
From NCERT
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NEET 2023 - Target Batch - Aryan Raj Singh

Atomic radius of silver is 144.5 pm. The unit cell of silver is a face centred cube. Calculate the density of silver.

(1) 10.50 g/cm3

(2) 16.50 g/cm3

(3) 12.30 g/cm3

(4) 15.50 g/cm3

Subtopic:  Density & Packing Fraction |
 55%
From NCERT
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A metallic element exists as a cubic lattice. Each edge of the unit cell is 2.88 Å. The density of the metal is 7.20 g cm–3.  The number of unit cells, that will be present in 100 gm of the metal is: 

1. 5.82 × 1023

2. 16.33 × 1023

3. 7.49 × 1024

4. 6.9 × 1024

Subtopic:  Density & Packing Fraction |
 53%
From NCERT
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Links
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Silver crystallizes in a face centred cubic system, 0.408 nm along each edge. The density of silver is 10.6 g/cm3 and the atomic mass is 107.9 g/mol. Calculate Avogadro's number.

(1) 6.00×1023 atom/mol

(2) 9.31×1023 atom/mol

(3) 6.23×1023 atom/mol

(4) 9.61×1023atom/mol

Subtopic:  Density & Packing Fraction |
 59%
From NCERT
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Fraction of total volume occupied by atoms in a simple cube is

(1) π2

(2) 3π8

(3) 2π6

(4) π6

Subtopic:  Density & Packing Fraction |
 80%
From NCERT
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