Q. No.Which of the following defects decreases the density?
(a) Interstitial defect
(b) Vacancy defect
(c) Frenkel defect
(d) Schottky defect
The correct choice among the given is-
1. (a, b)
2. (b, c)
3. (c, d)
4. (b, d)
Frenkel defect is also known as-
(a) Stoichiometric defect
(b) Dislocation defect
(c) Impurity defect
(d) Non-stoichiometric defect
1. (a, b)
2. (b, c)
3. (c, d)
4. (a, d)
In which of the following arrangements octahedral voids are formed?
(a) HCP
(b) BCC
(c) Simple cubic
(d) FCC
The correct choice among the above is -
1. (a, b)
2. (b, c)
3. (c, d)
4. (a, d)
Which of the following cannot be regarded as molecular solid?
(a) SiC (silicon carbide)
(b) AlN
(c) Diamond
(d) I2
The correct choice among the above is -
1. (a, b, c)
2. (b, c, d)
3. (a, c, d)
4. (a, b, d)
Incorrect statements regarding quartz glass are-
(a) This is a crystalline solid
(b) Refractive index is same in all the directions
(c) This has definite heat of fusion
(d) This is also called supercooled liquid
1. (a, b)
2. (b, c)
3. (c, d)
4. (a, c)
Select the correct option based on statements below:
| Assertion (A): | Semiconductors are solids with conductivities in the range from 10-6 — 104 ohm-1 m-1. |
| Reason (R): | Intermediate conductivity in semiconductors is due to a partially filled valence band. |
| 1. | Both (A) and (R) are true and (R) is the correct explanation of (A). |
| 2. | Both (A) and (R) are true but (R) is not the correct explanation of (A). |
| 3. | (A) is true but (R) is false. |
| 4. | (A) is false but (R) is true. |
Select the correct option based on statements below:
| Assertion (A): | The packing efficiency is maximum for the fcc structure. |
| Reason (R): | The coordination number is 12 in fcc structure. |
| 1. | Both (A) and (R) are true and (R) is the correct explanation of (A). |
| 2. | Both (A) and (R) are true but (R) is not the correct explanation of (A). |
| 3. | (A) is true but (R) is false. |
| 4. | (A) is false but (R) is true. |
Select the correct option based on statements below:
| Assertion (A): | Total number of octahedral voids present in the unit cell of cubic close packing including the one that is present at the body center, is four. |
| Reason (R): | Besides the body center there is one octahedral void present at the center of each of the six faces of the unit cell and each of which is shared between two adjacent unit cells. |
| 1. | Both (A) and (R) are true and (R) is the correct explanation of (A). |
| 2. | Both (A) and (R) are true but (R) is not the correct explanation of (A). |
| 3. | (A) is true but (R) is false. |
| 4. | (A) is false but (R) is true. |
Select the correct option based on statements below:
| Assertion (A): | Graphite is a good conductor of electricity. However, diamond belongs to the category of insulators. |
| Reason (R): | Graphite is soft in nature whereas diamond is very hard and brittle. |
| 1. | Both (A) and (R) are true and (R) is the correct explanation of (A). |
| 2. | Both (A) and (R) are true but (R) is not the correct explanation of (A). |
| 3. | (A) is true but (R) is false. |
| 4. | (A) is false but (R) is true. |
| Assertion (A): | The total number of atoms present in a simple cubic unit cell is one. |
| Reason (R): | Simple cubic unit cell has atoms at its corners, each of which is shared between eight adjacent unit cells. |
| 1. | Both (A) and (R) are true and (R) is the correct explanation of (A). |
| 2. | Both (A) and (R) are true but (R) is not the correct explanation of (A). |
| 3. | (A) is true but (R) is false. |
| 4. | (A) is false but (R) is true. |
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