Free Objective Test 02 Practice Test - 11th and 12th

Question 1

The Bat Life: What can be said with 100% confidence about the temperatures at point $P_{1} a n d P_{2}$ ?

$T_{P_{1}} = T_{P_{2}}$

$T_{P_{1}}$ > $T_{P_{2}}$

$T_{P_{1}}$ < $T_{P_{2}}$

$T_{P_{1}} \neq T_{P_{2}}$ .

SOLUTION

Solution : D

Just like a single macroscopic pressure being undefined for a gas which is not in equilibrium, a single macroscopic temperature is also undefined. So the temperature at $P_{1} a n d P_{2}$ need not necessarily be the same, and most likely wouldn't be the same.

Question 2

The Bat Life: Batman is undercover, and to prevent anyone from recognizing his voice (or Bruce Wayne's) he inhales a very dilute Helium gas (search YouTube for "voice after helium” to see the effects). The helium is stored ina cylindrical chamber as shown.

During a fight one of the steel balls gets dislodged. What will happen to the piston?

It will move down

It will move up

It will remain in the same place

Not enough information, only Batman will know

SOLUTION

Solution : B

Initial free body diagram -

.

When the system was in equilibrium, the force applied by the steel balls on the piston was offset by the force applied by the gas on the piston.

Just after removing the ball -

.

The instant the ball is dislodged the downward force acting on the piston reduces from 19.6 N $(i . e ., 2 \times 9.8 N) t o 14.7 N (1.5 \times 9.8 N)$ . However the pressure of the helium gas has not changed. Hence there is an unbalanced force in the upward direction. This upward force will push the piston up. After some time, the weight of the balls would equal the force exerted by the helium gas and the system would eventually come to rest.

Question 3

Which amongst the following graphs represents the V-T graph shown in the figure?

SOLUTION

Solution : C

Let us analyse each process separately. BC is an isothermal process, which implies that the P-C graph would be represented by a rectangular hyperbola. (Since PV = constant).

This rectangular hyperbola starts at a lower volume $V_{1}$ and goes to a higher volume as represented in the figure below -

Process AB is an isochoric process, which in a P-V graph would be a vertical line. Also we notice that the temperature drops in this process, whichimplies that the pressure will also drop (since PV=nRT, when V is constant $P \propto T$ ). Therefore point Acan be anywhere on the line represented in blue in the figure below.

Process C - A

This process is an isobaric process since it represents a curve where $V \propto T$ (this is possible only when pressure is a constant, remember Charles' law?). So the process can be represented by a horizontal line in a P-Vgraph. The point where the line joining process A-B and C-A meet is the point A.

Question 4

Which of these statements is/are true about internal energy (Eint) of a system of gas?

$E_{i n t}$ always increases as pressure increases

$E_{i n t}$ always decreases as temperature decreases

$E_{i n t}$ is proportional to volume

$E_{i n t}$ is proportional to the kinetic energy of the atoms in the system

SOLUTION

Solution : B and D

$E_{i n t}$ is defined as
$E_{i n t} = (\frac{3}{2}) k T \times N$
Eint is always going to increase when temperature is going to rise. The temperature of any system is the average kinetic energy of the atoms in the system.

Question 5

Tea contained in a mug is an example of:

Isolated system

Open system

Closed system

None

SOLUTION

Solution : B

Let's talk about the different kinds of system first.
Open system -matter and energy both can be transferred.
Closed system - Only energy can be transferred.
Isolated - Neither energy nor matter can be transferred.
A mug is a vessel, it allows for the exchange of matter and energy between the system and surroundings. Thus it is an open system.

Question 6

A system which exchanges both matter & energy with the surrounding is called a closed system.

True

False

SOLUTION

Solution : B

A system which exchanges both matter & energy with the surroundings is called an open system by definition.
Open system -matter and energy both can be transferred.
Closed system - Only energy can be transferred.
Isolated - Neither energy nor matter can be transferred.

Question 7

Fundamental properties which determine the state of a system are referred to as state variables.

True

False

SOLUTION

Solution : A

Fundamental properties which determine the state of a system are referred to as state variables or state functions or thermodynamic parameters. The change in the state properties depends only on the initial and final states of the system, but is independent of the manner in which the change has been brought about. In other words, the state properties do ont depend upon the path taken.

Question 8

Find the value of $Δ U$ .

A. +150 J

B. -50 J

C. +50 J

D. -150 J

SOLUTION

Solution : C

Take a minute and try to get this on your own. Then move on the next video for the explanation.

Question 9

Find the value of $Δ U$ .

A. +20 J

B. -80 J

C. +80 J

D. -20 J

SOLUTION

Solution : B

Take a minute and try to get this on your own. Then move on the next video for the explanation.

Question 10

Match the following:

$1. W_{A B}$ $I . 0$
$2. W_{B C}$ $I I . - 1500 J$
$3. W_{C A}$ $I I I . 1000 J$

1 - I, 2 - I I, 3 - I I I

1 - I I, 2 - I, 3 - I I I

1 - I I I, 2 - I, 3 - I I

1 - I I I, 2 - I I, 3 - I

SOLUTION

Solution : D

Take 2-3 minutes and try to get this on your own. Then move on the next video for the explanation.

Question 11

A process where the gas is taken from one state to another through infinitely small changes is called

equilibrium process

pseudo-equilibrium

adiabatic process

quasi-static process

SOLUTION

Solution : D

In thermodynamics, a quasi-static process is a thermodynamic process that happens slowly enough for the system to remain in internal equilibrium. Only in such processes can each moment be represented on the P-V diagram.

Free Objective Test 02 Practice Test - 11th and 12th

Question 1

SOLUTION

Question 2

SOLUTION

Question 3

SOLUTION

Question 4

SOLUTION

Question 5

SOLUTION

Question 6

SOLUTION

Question 7

SOLUTION

Question 8

SOLUTION

Question 9

SOLUTION

Question 10

SOLUTION

Question 11

SOLUTION

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