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 |
1. (I, II)
2. (II, III)
3. (III, IV)
4. (I, IV)