Q. No.The value of the magnetic moment is zero in the case of antiferromagnetic substances because the domains -
I.
Get oriented in the direction of the applied magnetic field
II.
Get oriented opposite to the direction of the applied magnetic field
III.
Are oppositely oriented with respect to each other without the application of magnetic field
IV.
Cancel out each other’s magnetic moment
The correct choice among the given is -
1. (I, II)
2. (II, III)
3. (III, IV)
4. (I, IV)
Incorrect(s) statement among the following:
| I. | Vacancy defect results in a decrease in the density of the substance. |
| II. | Interstitial defects results in an increase in the density of the substance. |
| III. | Impurity defect has no effect on the density of the substance. |
| IV. | Frenkel defect results in an increase in the density of the substance. |
1. (I, II)
2. (II, III)
3, (III, IV)
4. (I, IV)
The correct statements among the following about metals are-
| I. | Valence band overlaps with the conduction band. |
| II. | The gap between the valence band and conduction band is negligible |
| III. | The gap between the valence band and conduction band cannot be determined |
| IV. | Valence band may remain partially filled |
1. (I, II, III)
2. (II, III, IV)
3. (I, III, IV)
4. (I, II, IV)
Under the influence of the electric field, which of the following statement is true about the movement of electrons and holes in a p-type semiconductor?
| I. | Electron will move towards the positively charged plate through electron holes |
| II. | Holes will appear to be moving towards the negatively charged plate |
| III. | Both electrons and holes appear to move towards the positively charged plate |
| IV. | Movement of electrons is not related to the movement of holes |
The correct choice among the given is-
1. (I, II)
2. (II, III)
3. (III, IV)
4. (I, IV)
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
An excess of potassium ions makes KCl crystals appear violet or lilac in colour because-
| a. | Some of the anionic sites are occupied by an unpaired electron |
| b. | Some of the anionic sites are occupied by a pair of electrons |
| c. | There are vacancies at some anionic sites |
| d. | F-centres are created which impart colour to the crystals |
The correct choice among the given is-
1. (a, b)
2. (b, c)
3. (c, d)
4. (a, d)
The number of tetrahedral voids per unit cell in NaCl crystal is -
I. 4
II. 8
III. Twice the number of octahedral voids
IV. Four times the number of octahedral voids.
The correct choice among the given is-
1. (I, II)
2. (II, III)
3. (III, IV)
4. (I, IV)
Amorphous solids can also be called -
I. Pseudo solids
II. True solids
III. Supercooled liquids
IV. Supercooled solids
1. (I, II)
2. (II, III)
3. (III, IV)
4. (I, III)
A perfect crystal of silicon is doped with some elements as given in the options. Which of these options shows n-type semiconductors?
a. 
b. 
c. 
d. 
1. (a, b)
2. (b, c)
3. (c, d)
4. (a, c)
Which of the following statements is correct?
| I. | Ferrimagnetic substances lose ferrimagnetism on heating and become paramagnetic |
| II. | Ferrimagnetic substances do not lose ferrimagnetism on heating and remain ferrimagnetic |
| III. | Antiferromagnetic substances have domain structures similar to ferromagnetic substances and their magnetic moments are not canceled by each other |
| IV. | In ferromagnetic substances, all the domains get oriented in the direction of the magnetic field and remain as such even after removing the magnetic field |
The correct choice among the given is -
1. (I, II)
2. (II, III)
3. (III, IV)
4. (I, IV)
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