# How many number of tetrahedral voids are formed in 5 mol of a compound having cubic close packed structure? (Choose the correct option) 1. $$1.550 \times10^{24}$$ 2. $$3.011 \times10^{25}$$ 3. $$3.011 \times10^{24}$$ 4. $$6.022 \times10^{24}$$

Subtopic:  Voids, Radius Ratio & Coordination Number |
From NCERT
NEET - 2023
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How are edge length 'a' of the unit cell and radius 'r' of the sphere related to each other in ccp structure?
(Choose correct option for your answer)
 1 $$a = 2r$$ 2 $$a = r /2\sqrt2$$ 3 $$a = 4r /\sqrt3$$ 4 $$a = 2\sqrt2r$$
Subtopic:  Density & Packing Fraction |
From NCERT
NEET - 2023
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What fraction of one edge centred octahedral void lies in one unit cell of fcc?
 1 $$1 \over 12$$ 2 $$1 \over 2$$ 3 $$1 \over 3$$ 4 $$1 \over 4$$
Subtopic:  Voids, Radius Ratio & Coordination Number |
From NCERT
NEET - 2023
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A compound is formed by two elements A and B. The element B forms cubic close-packed structure and atoms of A occupy 1/3 of tetrahedral voids. If the formula of the compound is $$A_x B_y$$ then the value of x+y is in option
1.  2
2.  5
3.  4
4.  3
Subtopic:  Density & Packing Fraction |
54%
From NCERT
NEET - 2023
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Match List-I with List-II :
 List-I (Defects) List-II (shown by) (a) Frenkel defect (i) non-ionic solids and density of the solid decreases. (b) Schottky defect (ii) non-ionic solids and density of the solid increases. (c) Vacancy   defect (iii) ionic solids and density of the solid decreases. (d) Interstitial       defect (iv) ionic solids and the density of the solid remains constant.
Choose the correct answer from the options given below:
 (a) (b) (c) (d) 1. (i) (ii) (iii) (iv) 2. (i) (iii) (ii) (iv) 3. (iv) (iii) (ii) (i) 4. (iv) (iii) (i) (ii)
Subtopic:  Imperfections in Solids & Semiconductors |
72%
From NCERT
NEET - 2022
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Which statements among the following is not correct?

 1 When conduction band and valence band overlap, a semiconductor is obtained 2 Ferrimagnetism arises due to the alignment of magnetic moments of the domains in the substance in parallel and anti-parallel directions in unequal numbers 3 Replacing some silicon atoms by boron atoms in crystal of silicon produces p-type semiconductor 4 Replacing some germanium atoms by phosphorus atoms in a crystal of germanium produces n-type semiconductor
Subtopic:  Imperfections in Solids & Semiconductors |
71%
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NEET - 2022
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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 opposite to the direction of magnetic field. 2 domains are not affected by magnetic field. 3 domains get randomly oriented. 4 all the domains get oriented in the direction of magnetic field.

Subtopic:  Magnetic Behaviour of an Element/Compound |
78%
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NEET - 2022
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Copper crystallises in fcc unit cell with a cell edge length of $$3.608 \times 10^{-8}$$ cm. The density of copper is $$8.92 \ g ~cm^{-3}$$. The atomic mass of copper is:

1. 65 u
2. 63.1 u
3. 31.55 u
4. 60 u
Subtopic:  Density & Packing Fraction |
69%
From NCERT
NEET - 2022
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Select the correct option based on statements below:
 Assertion (A): In a particular point defect, an ionic solid is electrically neutral, even if few of its cations are missing from its unit cells. Reason (R): In an ionic solid, Frenkel defect arises due to dislocation of cation from its lattice site to interstitial site, maintaining overall electrical neutrality.

 1 (A) is false but (R) is true. 2 Both (A) and (R) are true and (R) is the correct explanation of (A). 3 Both (A) and (R) are true but (R) is not the correct explanation of (A). 4 (A) is true but (R) is false.
Subtopic:  Imperfections in Solids & Semiconductors |
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NEET - 2022
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The correct option for the number of body centred unit cells in all 14 types of Bravais lattice unit cells is :

1. 2

2. 3

3. 7

4. 5

Subtopic:  Introduction & Crystal System |
54%
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NEET - 2021
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