NUST Medical Chapter 17 + 18 + 19 Chemistry
NUST (Medical)
CHAPTER
17+18+19
(1)
Which of the following graphs represent the
variation of particle momentum and the associated de-Broglie wavelength?
(a)
(b) (c) (d)
(2)
In an operational amplifier as a night switch
the potential across the LDR during night
(a) increases (b) decreases (c) remains constant (d) becomes zero
(3)
Stopping potential for photoelectrons.
(a) does not depend on the nature of cathode material
(b) does not depend on the frequency of the incident
light
(c) depends on both the frequency of the incident light and the nature of
the cathode material
(d) depends on the intensity of the incident light
(4)
All magnetic materials lose their magnetic properties
when
(a) dipped in water (b)
dipped in oil
(c) strongly
heated (d) brought
near a piece of iron
(5)
Bonding in a germanium crystal is
(a) metallic (b)
ionic (c) covalent (d) none of these
(6)
The p-side of a junction diode is earthed and
the n-side is given a potential of –2V. The diode will
(a) break down (b) conduct (c) not conduct (d)
conduct partially
(7)
The truth table
A B Y
0 0 1
1 0 0
0 1 0
1 1 0
corresponds to
(a) NAND gate (b) NOR gate (c) AND gate (d)
NOT gate
(8)
A photon of energy 1.5MeV collides with a heavy
nucleus which of the following is the dominant phenomenon
(a) Compton’s effect (b) pair production
(c) photoelectric effect (d) all are equally probable
(9)
The area of hysteresis loop is an indication of
(a) coercivity of the material (b) retentivity of the
material
(c) energy
dissipated per cycle (d)
none of these
(10)
Soft iron is preferred for the core of a
transformer because it has
(a) large coercivity (b) large
retentivity (c) large loop area (d) small loop area
(11)
Super conductors offers
(a) little resistance to electric current (b) large resistance to electric current
(c) no resistance to electric
current (d)
moderate resistance to electric current
(12)
In a pnp transistor, the p-type crystal acts as
(a) emitter only (b)
collector only
(c) either emitter or collector
(d) neither
emitter nor collector.
(13)
The current gain in a common emitter transistor
is
(a) more than 1 (b) less than 1 (c) equal to 1 (d) zero
(14)
In an intrinsic semi conductor the number of
(a) electrons are greater (b)
holes are greater
(c) electrons and holes are equal (d) none of these
(15)
In the depletion region of an unbiased pn
junction diode, there are
(a) only electrons (b)
only holes
(c) both electrons and holes (d) only fixed ions
(16)
When n-type semiconductor is heated, the
(a) number of electrons increases while that of holes decreases
(b) number of holes increases white that of electrons decreases
(c) number of electrons and holes remains the same
(d) number of electrons and holes
increases equally.
(17)
In the case of forward biasing of pn junction,
which one of the following figures correctly depicts the direction of the flow
of charge carriers?
(a) (b)
(c) (d)
(18)
A semiconducting device is connected in a series
circuit with a battery and a resistance. A current is found to pass through the
circuit. If the polarity of the battery is reversed, the current drops to
almost zero. The device may be
(a) a pn junction (b)
an intrinsic semiconductor
(c) a p-type semiconductor (d) an n-type semiconductor
(19)
Two identical p-n junction may be connected in
series with a battery in three ways. The potential drops across the two p-n
junctions are equal in
circuit
1 circuit
2 circuit
3
(a) circuit 1 and circuit 2 (b) circuit 2 and circuit 3
(c) circuit 3 and circuit 1 (d) circuit 1 only.
(20)
Which of the following groups represents
polymeric solids
(a) glass,
polystyrene, nylon (b)
polystrene, rubber, sodium chloride
(c) glass, gold, polythene (d) polythene, rubber, nylon
(21)
The de-Broglie wavelength of a neutron when its
kinetic energy is K is λ. What will be its wavelength when its kinetic energy
is 4K?
(a)
(b)
(c)
2l (d) 4l
(22)
Moving
with the same velocity, which of the following has the longest de-Broglie
wavelength?
(a) b-particle (b) a-particle (c) proton (d)
neutron
(23)
The temperature at which a ferromagnetic
material becomes paramagnetic is called
(a) critical temperature (b)
inversion temperature
(c) neutral temperature (d) curie temperature
(24)
The maximum kinetic energy of photoelectrons
emitted from a surface when photons of energy 6eV fall on it is 4eV. The
stopping potential is
(a) 2V (b) 4V (c) 6V (d)
10V
(25)
No of
inputs in NOT gate are
(a) one (b) two (c) three (d) four
(26)
Crystalline solids have
(a) long range order and no definite melting point
(b) long range order and sharp
melting point
(c) short range order and sharp melting point
(d) none of these
(27)
Boolean expression for NOR gate is
(a) A . B = Y (b) A+B
= Y (c)
(d)
(28)
A hole in a p-type semi conductor is
(a) an excess electron (b) a
missing electron (c) a missing atom (d)
an excess atom
(29)
The work functions for three different metal A,B
and C are fa,
fb
and fc
respectively with fa > fb > fc.
The graphs between stopping potential (Vo) and frequency of incident
radiation for them would look like
(a) (b) (c)
(d)
(30)
The electron, accelerated by a potential
difference V has de-Broglie wavelength l. If the electron is
accelerated by a p.d.4v, its de-Broglie wavelength will be
(a) 2l
(b) 4l (c)
(d)
(31)
The majority current carriers are
(a) electrons in p-type semiconductors and holes in n-types semi-conductors
(b) electrons in n-type
semiconductors and holes in p-type semiconductors (c) electrons in both p
and n type semiconductors
(d) holes in both p and n type semiconductors.
(32)
At
absolute zero of temperature, the electrical conductivity of a pure
semiconductor is
(a) zero (b) about 103
(Wm)-1 (c) about 107 (Wm)-1 (d) infinity
(33)
Choose the only incorrect statement from the
following
(a) in conductors, the valence and conduction bonds may overlap
(b) substances with an energy gap of the order of 10eV are insulators
(c) the resistivity of a
semiconductor increases with increase in temperature
(d) the conductivity of a semiconductor increases with increase in
temperature.
(34)
If a rubber ball is taken down to a 100m deep
lake its volume decreases by 0.1% if g =
10m.sec2 then bulk modulus of elasticity for rubber in N/m2
is
(a) 105 (b)
106 (c)
108 (d) 109
(35)
The addition of a minute quantity of antimony to
a silicon crystal makes it
(a) a good insulator (b)
a good conductor
(c) a p-type semiconductor (d) an n-type semiconductor
(36)
The p-n junction diodes are used as
(a) amplifiers to ‘build up’ a given ac signal
(b) rectifiers to change ac to dc
in power supplies
(c) oscillators to produce ac signals of desired amplitude and frequency
(d) none of these
(37)
The output from a full wave rectifier is
(a) an ac voltage (b)
a dc voltage
(c) zero (d) a pulsating unidirectional voltage
(38)
A half wave rectifier is being used to rectify
an alternating voltage of frequency 50 Hz. The number of pulses of rectified
current obtained in one second is
(a) 50 (b) 25 (c) 100 (d) 200
(39)
A piece of copper and another of germanium are
cooled from room temperature to 80 K. The resistance of
(a) each of them increases (b)
each of them decreases
(c) copper increases and that of germanium decreases
(d) copper decreases and that of
germanium increases.
(40)
In a typical transistor, the collector current
is
(a) slightly less than the
emitter current (b)
slightly more than the emitter current
(c) equal to the emitter current (d)
equal to the base current.
(41)
Which one of the following graphs in the figure
shows the variation of photoelectric current (I) with intensity of light in
photo electric cell
(a)
(b)
(c)
(d)
(42)
For a photoelectric cell, the graph in the
figure showing the variation of the cut off voltage Vo with frequency (v) of
incident light is
(a) (b)
(c) (d)
(43)
At
which relativistic speed the mass of an object will be come double than its
rest mass
(a)
(b)
(c)
(d)
(44)
The
work function for aluminium surface is 4.2eV and that the sodium surface is 2.0
eV. The two metals were illuminated with appropriate radiation so as to cause
photo emission then
(a) both aluminium and sodium will have the same threshold frequency
(b) the threshold frequency of
aluminium will be more than that of sodium
(c) the threshold frequency of aluminium will be less than that of
sodium
(d) the threshold wavelength of aluminium will be more than that of
sodium
(45)
A crystal lattice is
(a) a random arrangement of atoms in a crystal
(b) a random arrangement of molecules in a crystal
(c) an ordered arrangement of
points in space
(d) a piece of crystal
(46)
The photoelectrons emitted from a metal surface
(a) are all at rest
(b) have the same kinetic energy
(c) have the same momentum
(d) have speeds varying from zero
upto a certain maximum value
(47)
Violet light can cause photoelectric emission
from a metal but blue light cannot. If sodium light is incident on the metal,
then
(a) the photoelectric current decreases
(b) the number of photoelectrons ejected per second increases
(c) the velocity of photoelectrons increases
(d) no photoelectric emission
occurs
(48)
In common emitter amplifier the phase difference
between input signal voltage and out put voltage is
(a) 0 (b)
(c)
(d) p
(49)
A
proton and an electron move with the same velocity, the associated wavelength
for proton is
(a) shorter than that of the
electrons (b) longer
than that of the electrons
(c) the same as that of the electrons (d)
zero
(50)
The
number of crystal systems based upon the geometrical arrangement of atoms are
(a) three (b)
five (c) seven (d) nine
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