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. |
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. |
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): | 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): | 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. |
Match the type of packing given in Column I with the items given in Column II.
Column I | Column II |
A. Square close packing in two dimensions | 1. Triangular voids |
B. Hexagonal close packing in two dimensions | 2. Pattern of spheres is repeated in every fourth layer |
C. Hexagonal close packing in three dimensions | 3. Coordination number = 4 |
D. Cubic close packing in three dimensions | 4. Pattern of sphere is repeated in alternate layers |
Codes
A | B | C | D | |
1. | 3 | 2 | 4 | 1 |
2. | 1 | 2 | 3 | 4 |
3. | 3 | 1 | 4 | 2 |
4. | 4 | 1 | 3 | 2 |
Match the items given in Column I with the items given in Column II.
Column I | Column II |
A. Mg in solid state | 1. p-type semiconductor |
B. MgCl2 in molten state | 2. n-type semiconductor |
C. Silicon with phosphorus | 3. Electrolytic conductors |
D. Germanium with boron | 4. Electronic conductors |
Codes
A | B | C | D | |
1. | 2 | 3 | 4 | 1 |
2. | 1 | 2 | 3 | 4 |
3. | 1 | 4 | 3 | 2 |
4. | 4 | 3 | 2 | 1 |
Match the types of defects given in Column I with the statement given in Column II.
Column I | Column II |
A. Impurity defect | 1. NaCl with anionic sites called F-centres |
B. Metal excess defect | 2. FeO with Fe3+ |
C. Metal deficiency defect | 3. NaCl with Sr2+ and some cationic sites vacant |
Codes
A | B | C | |
1. | 2 | 3 | 1 |
2. | 3 | 1 | 2 |
3 | 1 | 2 | 3 |
4. | 2 | 1 | 3 |
Match the defects given in Column I with the statements given in Column II.
Column I | Column II |
A. Simple vacancy defect | 1. Shown by non-ionic solids and increases the density of the solid |
B. Simple interstitial defect | 2. Shown by ionic solids and decreases the density of the solid |
C. Frenkel defect | 3. Shown by non-ionic solids and decreases the density of the solid |
D. Schottky defect | 4. Shown by ionic solids and density of the solid remains the same |
Codes
A | B | C | D | |
1. | 3 | 1 | 4 | 2 |
2. | 1 | 2 | 3 | 4 |
3. | 1 | 4 | 3 | 2 |
4. | 4 | 1 | 3 | 2 |
Consider the following statements about semiconductors.
I. | Silicon doped with electron-rich impurity is a p-type semiconductor. |
II. | Silicon doped with an electron-rich impurity is an n-type semiconductor. |
III. | Delocalised electrons increase the conductivity of doped silicon. |
IV. | An electron vacancy increases the conductivity of n-type semiconductor. |
1. I and II
2. II and III
3. III and IV
4. I and IV