Statement of First Law of Thermodynamics MCQ Quiz in मल्याळम - Objective Question with Answer for Statement of First Law of Thermodynamics - സൗജന്യ PDF ഡൗൺലോഡ് ചെയ്യുക
Last updated on Mar 9, 2025
Latest Statement of First Law of Thermodynamics MCQ Objective Questions
Top Statement of First Law of Thermodynamics MCQ Objective Questions
Statement of First Law of Thermodynamics Question 1:
The statement which is NOT a consequence of the first law of thermodynamics is:
Answer (Detailed Solution Below)
Statement of First Law of Thermodynamics Question 1 Detailed Solution
Concept:
- Heat is a path function – TRUE → results from the first law.
- Energy is a property of the system- TRUE → results from the first law.
- Energy of an isolated system is conserved, as Q = W = 0 so ∆U = 0 implying U = const.
- A perpetual motion machine of the first kind is not possible – TRUE → corollary of the first law.
Statement of First Law of Thermodynamics Question 2:
According to the first law of thermodynamics, the internal energy for an ideal gas in an isothermal process is __________.
Answer (Detailed Solution Below)
Statement of First Law of Thermodynamics Question 2 Detailed Solution
Explanation:
- The internal energy of a system is the energy contained within the system. The internal energy of an ideal gas is a function of absolute temperature only.
For an ideal gas
U = f(T) only
Change in internal energy is given as
ΔU = mcΔT
ΔT = 0 ⇒ ΔU = 0
- In the case of the isothermal process, there is no change in temperature so change in internal energy is also zero.
So, Temperature will be constant in isothermal process.
Statement of First Law of Thermodynamics Question 3:
In a general compression process, 2 kJ of mechanical work is supplied to 4 kg of fluid and 800 J of heat is rejected to the cooling jacket. The change in specific internal energy would be
Answer (Detailed Solution Below)
Statement of First Law of Thermodynamics Question 3 Detailed Solution
From the first law of thermodynamics
dQ = dU + dW
dQ = -800 J ( As the heat is rejected from the system)
dW = -2000 J ( as work is supplied to system)
Change in internal energy = dQ – dW = -800 – (-2000) = 1200 J
Change in specific internal energy = 1200/4 = 300 J/kg (mass is 4 kg )Statement of First Law of Thermodynamics Question 4:
If the work done on a closed system is 40 kJ/kg, and heat rejected from the system is 80 kJ/kg, then its internal energy is _____.
Answer (Detailed Solution Below)
Statement of First Law of Thermodynamics Question 4 Detailed Solution
Concept:
- The first law of thermodynamics is a restatement of the law of conservation of energy.
- It states that energy cannot be created or destroyed in an isolated system; energy can only be transferred or changed from one form to another.
When heat energy is supplied to a gas, two things may occur:
- The internal energy of the gas may change
- The gas may do some external work by expanding
According to the first law of Thermodynamics:
δQ = δW + ΔU
Where δQ is change in heat, δW is work done, and ΔU is internal energy change.
Calculation:
Given:
Work done on a closed system = - 40 kJ
Heat rejected from the system = - 80 kJ
From the First law of thermodynamics
dQ = dW + ΔU
∴ dU = dQ – dW
∴ dU = -80 – (-40)
∴ dU = -40 kJ
So option 2 is correct.
Statement of First Law of Thermodynamics Question 5:
Correct statement for First law of thermodynamics
Answer (Detailed Solution Below)
Statement of First Law of Thermodynamics Question 5 Detailed Solution
Explanation:
The first law of thermodynamics is a version of the law of conservation of energy, adapted for thermodynamic systems. The law of conservation of energy states that the total energy of an isolated system is constant. Energy can be transformed from one form to another but cannot be created or destroyed.
The first law is often formulated by stating that the change in the internal energy of a closed system is equal to the amount of heat supplied to the system, minus the amount of work done by the system on its surroundings
δQ = ΔU + δW
ΔU = δQ - δW
According to the First Law of thermodynamics, “For a closed system undergoing a cycle, net heat transfer is equal to network transfer.”
ΣQ = ΣW.
Statement of First Law of Thermodynamics Question 6:
A stationary mass of gas is compressed without friction from an initial state of 0.3 m3 and 0.105 MPa to a final state of 0.15 m3 and 0.105 MPa, the pressure remaining constant during the process. There is a transfer of 37.6 kJ of heat from the gas during the process. How much does the internal energy of the gas change?
Answer (Detailed Solution Below)
Statement of First Law of Thermodynamics Question 6 Detailed Solution
Concept:
The equation of 1st Law of Thermodynamics for a closed system undergoing the change of state is given by:
Q1-2 = (U2 - U1) + W1-2
Q1-2 = \(Δ\)U + W1-2
Work Done During Constant Pressure (Isobaric Process) is given by:
W1-2 = P(V2 - V1)
where, Q1-2 = Heat Transfer during change of State, ΔU = Change in Internal Energy, W1-2 = Work Done during change of State, P = Pressure, V1, V2 = Initial and Final Volume
Sign Convection of Heat Transfer:
- If Heat is Transferred to the System then it is Positive.
- If Heat is Transferred from the System then it is Negative.
Calculation:
Given:
Q1-2 = -37.6 KJ, P = 0.105 MPa, V1 = 0.3 m3, V2 = 0.15 m3
-37.6 = \(Δ\)U + 0.105 × 1000 × (0.15-0.3)
-37.6 = \(Δ\)U -15.75
\(Δ\)U = -37.6 + 15.75
\(Δ\)U = -21.85 KJ
Statement of First Law of Thermodynamics Question 7:
A steel ball of mass 1 kg and specific heat 0.4 kJ/kgK is at a temperature of 60°C. It is dropped into 1 kg water at 20°C. The final steady state temperature of water is
Answer (Detailed Solution Below)
Statement of First Law of Thermodynamics Question 7 Detailed Solution
Concept:
When two bodies one hot and another cold comes into contact with each other then there is heat exchange between the two, and the heat lost by the hot body will be absorbed by the cold body.
(mcdT)ball = (mcdT)water
Calculation:
Given:
For ball, mass = 1 kg, specific heat = 0.4 kJ/kg, T = 60°C.
For water, mass = 1 kg, T = 20°C.
Let Tf is the final temperature obtained by the body and water, then
Heat given by ball = Heat taken by water
(mc dT)ball = (mc dt)water
1 × 0.4 × (60 – Tf) = 1 × 4.18 × (Tf - 20)
24 – 0.4Tf = 4.18Tf – 83.6
24 + 83.6 = [4.18 + 0.4] Tf
\(T_f = \frac{{24 + 83.6}}{{4.58}} = 23.5^\circ C\)Statement of First Law of Thermodynamics Question 8:
With respect to the first law of thermodynamics, which of the following statements is the most relevant
Answer (Detailed Solution Below)
Statement of First Law of Thermodynamics Question 8 Detailed Solution
Explanation:
The first law of thermodynamics is a version of the law of conservation of energy, adapted for thermodynamic systems.
The law of conservation of energy states that the total energy of an isolated system is constant. Energy can be transformed from one form to another but cannot be created or destroyed.
Additional Information
The first law is often formulated by stating that the change in the internal energy of a closed system is equal to the amount of heat supplied to the system, minus the amount of work done by the system on its surroundings
δQ = ΔU + δW
ΔU = δQ - δW
According to the First Law of Thermodynamics, “For a closed system undergoing a cycle, net heat transfer is equal to network transfer.”
ΣQ = ΣW
Statement of First Law of Thermodynamics Question 9:
Interpret the following statement to accurately identify the correct option:
"When heat is converted from one form to another, some energy is lost. As a result the total heat provided to a system does not equal the work performed by the system."
Answer (Detailed Solution Below)
Statement of First Law of Thermodynamics Question 9 Detailed Solution
Explanation:
The first law of thermodynamics is a restatement of the law of conservation of energy. It states that energy cannot be created nor destroyed in an isolated system; energy can only be transferred or changed from one form to another.
When heat energy is supplied to a gas, two things may occur:
- The internal energy of the gas may change
- The gas may do some external work by expanding
According to the first law of Thermodynamics:
δQ = δW + ΔU
When heat is converted from one form to another, some energy is lost or used to increase internal Energy As a result, the total heat provided to a system does not equal the work performed by the system
ΔU = δQ – δW where U is the internal energy which is introduced by this law.
For the cyclic process: ΔU = 0
\(\oint \delta Q = \oint \delta W\)
The first law of thermodynamics states that for a cyclic process, the cyclic integral of heat is equal to the cyclic integral of work.
The second law of thermodynamics introduces the concept of entropy.
Statement of First Law of Thermodynamics Question 10:
The concept of internal energy is given by the _______.
Answer (Detailed Solution Below)
Statement of First Law of Thermodynamics Question 10 Detailed Solution
CONCEPT:
The first law of thermodynamics:
- The first law of thermodynamics states that the change in internal energy of a system is equal to the sum of the heat exchanged with the surroundings and the amount of work done by the surrounding on the system.
⇒ Q = W + ΔU
Where U = internal energy of the system, Q = amount of heat, and W = work done
- The first law of thermodynamics gives the concept of internal energy.
EXPLANATION:
- We know that the first law of thermodynamics gives the concept of internal energy. Hence, option 1 is correct.
Additional Information
Second Law of Thermodynamics:
- Clausius statement: It is impossible for a self-acting machine to transfer heat from a colder body to a hotter one without the aid of an external agency
- The Kelvin-Plack statement of the second law of thermodynamics states that " it is impossible for the cyclic device to absorb heat energy from a single reservoir and to deliver equivalent amount heat "
- A heat engine is a device that converts the heat into work
- The efficiency of the heat engine is given by
\(η = 1 - \frac{Q_{2}}{Q_{1}}\)
Where Q2 = Heat rejected into the sink, Q1= Heat absorbed by working substance