Heat and thermodynamics is last chapter of first year Physics book.This chapter holds quite an importance in board's exam.
Heat and thermodynamics MCQs
1.
The Avogadro number represents the number of
atoms
in
(a)
1 kg of a substance (b)
unit volume of a substance
(c)
1 mole of a substance (d) total
amount of a substance
2.
Molecules of a mono atomic gas possess
(a)
rotational motion (b)
vibrational motion
(c)
translational motion (d) all of these
3.
A closed system is one in which
(a)
the energy of the system remains constant
(b)
the mass of the system remains the same
(c)
both mass and energy of the system remain the
same
(d)
nether mass nor energy remain the same
4.
In a thermodynamical process the change in
internal energy depends upon (a) the initial state only
(b) the
final state only
(c) the
path followed by the change
(d) the
initial and the final state
5.
The equation PV = constant holds in
(a)
isothermal process (b)
isochoric process
(c) adiabatic process (d) all of these
6.
In a Carnot engine, the final temperature of the
working substance is
(a)
greater than its initial temperature
(b)
smaller than its initial temperature
(c)
equal to its initial temperature
(d)
zero
7.
The working substance of a Carnot engine is
(a)
source (b) sink
(c) petrol (d)
ideal gas
8.
Upon decreasing the temperature of the sink, the
efficiency of the Carnot engine
(a)
decreases
(b)
does not change
(c) increases (d) none of these
9.
When the temperature of source and the sink
become equal the change in entropy of a Carnot engine becomes
(a)
zero (b)
minimum
(c) maximum (d) negative
10.
All real heat engines are less efficient than a
Carnot engine due to
(a)
working substance
(b)
temperature of the reservoirs
(c)
friction and heat losses
(d)
all of these
11.
The unit of thermodynamic temperature is
(a)
K (b) OF
(c) OC (d) none of these
13.
Human metabolism provides a good example of
(a)
mass conservation
(b)
energy conservation
(c)
entropy conservation
(d)
none of these
14.
The increase in thermal pollution of
environments means
(a)
a decrease in entropy
(b)
an increase in entropy
(c)
constant entropy
(d)
none of these
15.
Upon shifting a simple pendulum from Karachi to
Mount
Everest, its natural frequency
(a)
increases (b)
decreases
(c)
remains the same (d) none of these
16.
Under similar conditions of temperature and
pressure, the velocity of sound will be maximum in
(a)
oxygen (b) hydrogen.
(c) nitrogen (d)
carbon dioxide
17.
Presence of moisture in air
(a)
increases the velocity of sound
(b)
decreases the velocity of sound
(c)
has no effect on the speed of sound
(d)
none of these
18.
A string of length l fixed at both ends is
plucked from its middle so that it vibrates in one loop. The
wavelength of the wave in this mode is
(a)
l/2 (b)
l
(c) 2l (d)
l/4
19.
The ratio of the fundamental frequency of a organ pipe open at both ends to an organ
pipe closed at both ends is
(a)
2:1 (b)
1:2
(c) 1:1 (d) 3:1
20.
When a simple pendulum swings, which of the
following quantities is not zero throughout the motion?
(a)
Acceleration
(b)
Speed
(c) Weight (d)
Momentum
21.
A string with one end fixed is being whirled
from the other free end so that it vibrates with the fundamental frequency of
20 Hz. Its next harmonic has a frequency
equal to
(a)
40 Hz (b) 60 Hz
(c) 10 Hz (d)
neither of these
22.
In an interference pattern
(a)
bright fringes are wider than dark fringes
(b)
dark fringes are wider than the bright fringes
(c)
both dark and bright fringes are of equal width
(d)
none of these
23.
In a diffraction pattern, the fringes are
(a)
equally spaced
(b)
wider near the object and narrower away from it
(c)
narrower near the object and wider away from
it
(d)
none of these
24.
The Celsius and Fahrenheit scales have the same
reading at
(a)
40o (b)
140o
(c) 40o (d) 140o
25.
Absolute zero is considered to be the
temperature at which
(a)
all gases become liquid
(b)
all liquids become solid
(c)
water freezes
(d)
molecular motion in gases ceases
26.
Which of the followings do not have the same
units?
(a)
Mechanical energy
(b)
Kinetic energy
(c)
Heat energy
(d)
Power
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