40
MCQ (Multiple Correct Answer)
Which of the following statements are not true?
A
Vacancy defect results in a decrease in the density of the substance
B
Interstitial defects results in an increase in the density of the substance
C
Impurity defect has no effect on the density of the substance
D
Frenkel defect results in an increase in the density of the substance
41
MCQ (Multiple Correct Answer)
Which of the following statements are true about metals?
A
Valence band overlaps with conduction band
B
The gap between valence band and conduction band is negligible
C
The gap between valence band and conduction band cannot be determined
D
Valence band may remain partially filled
42
MCQ (Multiple Correct Answer)
Under the influence of electric field, which of the following statement is true about the movement of electrons and holes in a p-type semiconductor?
A
Electron will move towards the positively charged plate through electron holes
B
Holes will appear to be moving towards the negatively charged plate
C
Both electrons and holes appear to move towards the positively charged plate
D
Movement of electrons is not related to the movement of holes
43
MCQ (Multiple Correct Answer)
Which of the following statements are true about semiconductors?
A
Silicon doped with electron rich impurity is a $p$-type semiconductor
B
Silicon doped with an electron rich impurity is an $n$-type semiconductor
C
Delocalised electrons increase the conductivity of doped silicon
D
An electron vacancy increases the conductivity of $n$-type semiconductor
44
MCQ (Multiple Correct Answer)
An excess of potassium ions makes KCl crystals appear violet or lilac in colour since .............. .
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