Thermodynamics NEET Questions: Answer Key, PDF
Thermodynamics is a crucial topic in the NEET syllabus, encompassing key principles just like the legal guidelines of thermodynamics, warmness switch, and thermodynamic approaches. Students can anticipate questions that assess their information of principles together with enthalpy, entropy, and the relationships between temperature, strain, and extent in gases. Mastery of thermodynamic equations and problem-fixing competencies is vital for fulfillment in NEET. Practicing numerous question kinds will decorate students’ analytical talents and alertness of thermodynamic principles in biological systems.
Introduction to Thermodynamics
Thermodynamics is a fundamental branch of physics that plays a crucial position in information strength switch, warmth, and paintings in chemical and physical techniques. For NEET aspirants, getting to know thermodynamics is essential, because it forms a widespread portion of the syllabus, specifically in topics associated with physical chemistry and biology. Questions on thermodynamics assess college students’ grasp of ideas including the laws of thermodynamics, enthalpy, entropy, and Gibbs loose power. These standards not simplest aid in fixing numerical problems but also in applying theoretical information to actual-global biological systems, such as metabolic pathways and enzyme pastime. By focusing on thermodynamics NEET questions, college students can beautify their hassle-fixing skills and put together correctly for this tough exam.
Key Concepts and Terminology
Some essential principles in thermodynamics consist of:
- System: The part of the universe being studied.
- Surroundings: Everything outdoor the machine.
- State: The condition of a device defined by means of its houses (e.g., temperature, stress, volume).
- Equilibrium: A nation where the device’s homes aren’t changing with time.
- Thermodynamic procedure: A change in the kingdom of a machine.
- Internal power: The overall electricity of a machine, which includes kinetic and capacity electricity of its debris.
- Heat: Energy transferred between a device and its environment because of a temperature difference.
- Work: Energy transferred among a machine and its surroundings due to a pressure acting via a distance.
- First regulation of thermodynamics: Energy can neither be created nor destroyed; it could best be transferred or converted. Mathematically, ΔU = Q – W, in which ΔU is the alternate in internal electricity, Q is the warmth added to the device, and W is the work accomplished by using the device.
- Second law of thermodynamics: Heat flows spontaneously from a hotter object to a colder one. It is not possible to transform all heat into paintings without some power being wasted.
Download: Thermodynamics
| TitleThermodynamics | Download |
|---|---|
| Thermodynamics NEET Questions with Answer | Click |
Laws of Thermodynamics
| Law | Statement | Mathematical Expression |
|---|---|---|
| Zeroth Law | If two systems are in thermal equilibrium with a third system, then they are in thermal equilibrium with each other. | – |
| First Law | Energy can neither be created nor destroyed; it can only be transferred or transformed. | ΔU = Q – W |
| Second Law | Heat flows spontaneously from a hotter object to a colder one. It is impossible to convert all heat into work without some energy being wasted. | ΔS ≥ 0 (for an isolated system) |
| Third Law | It is impossible to reduce the temperature of a system to absolute zero in a finite number of steps. | As T → 0, ΔS → 0 |
Thermodynamic Systems and Processes
| System Type | Definition | Example |
|---|---|---|
| Open System | A system that can exchange both matter and energy with its surroundings. | A pot of boiling water |
| Closed System | A system that can exchange energy with its surroundings but not matter. | A sealed container of gas |
| Isolated System | A system that cannot exchange either matter or energy with its surroundings. | An ideal thermos |
| Process Type | Definition | Mathematical Condition |
|---|---|---|
| Isothermal Process | A process that occurs at constant temperature. | ΔT = 0 |
| Adiabatic Process | A process that occurs without heat transfer. | Q = 0 |
| Isobaric Process | A process that occurs at constant pressure. | ΔP = 0 |
| Isochoric Process | A process that occurs at constant volume. | ΔV = 0 |
Thermodynamic Properties
Internal Energy (U)
- Definition: The general power of a machine, along with kinetic and capacity strength of its debris.
- Units: Joules (J)
- Factors affecting: Temperature, strain, quantity, and the range of debris in the device.
Enthalpy (H)
- Definition: A thermodynamic property that may be a combination of internal energy and the product of pressure and extent.
- Formula: H = U + PV
- Units: Joules (J)
- Used for: Measuring the warmth absorbed or released in a manner at regular pressure.
Entropy (S)
- Definition: A measure of the disorder or randomness of a system.
- Units: Joules consistent with Kelvin (J/K)
- Increases: When a system turns into extra disordered (e.g., melting of a solid).
- Decreases: When a machine turns into extra ordered (e.g., freezing of a liquid).
Specific Heat Capacity (c)
- Definition: The amount of heat required to raise the temperature of one unit mass of a substance by one degree Celsius.
- Units: Joules per kilogram-Kelvin (J/kg·K)
Types:
- Specific heat capacity at constant pressure (cp): Used for processes at constant pressure.
- Specific heat capacity at constant volume (cv): Used for processes at constant volume.
Relationship between cp and cv:
cp – cv = R (for ideal gases), where R is the ideal gas constant.
Heat Engines and Refrigerators
| Topic | Description |
|---|---|
| Carnot Engine | The Carnot engine is a theoretical thermodynamic cycle proposed by Nicolas Léonard Sadi Carnot. It is the most efficient heat engine cycle, with the highest possible efficiency, operating between two temperatures. |
| Refrigeration Cycle | The refrigeration cycle is a process that removes heat from a low-temperature reservoir and transfers it to a high-temperature reservoir, commonly used in refrigerators and air conditioners. |
| Coefficient of Performance (COP) | The coefficient of performance is a measure of the efficiency of a refrigerator or heat pump. It is the ratio of the heat removed or added to the work input. |
| Efficiency of Heat Engines | The efficiency of a heat engine is the ratio of work output to the heat input, typically less than 100%, as some energy is lost as waste heat. |
Equations and Calculations
Work Done in Thermodynamic Processes
General equation: W = ∫PdV
wherein W is the work performed, P is the strain, and V is the volume.
Specific instances:
- Isobaric system: W = PΔV
- Isochoric system: W = 0
- Isothermal procedure: W = nRT ln(V2/V1)
wherein n is the range of moles, R is the correct gasoline regular, and T is the temperature.
Heat Transfer Calculations
General equation: Q = mcΔT
wherein Q is the warmth transferred, m is the mass, c is the unique warmness capacity, and ΔT is the change in temperature.
For a method at regular strain (enthalpy exchange): Q = ΔH
Enthalpy Changes
- Enthalpy of a response (ΔH_rxn): The distinction between the enthalpies of the products and the reactants.
- Enthalpy of formation (ΔH_f): The enthalpy change whilst one mole of a compound is fashioned from its elements in their fashionable states.
- Hess’s law: The enthalpy change for a response is the identical whether it occurs in one step or a series of steps.
Example:
To calculate the enthalpy change for the response: A + B → C
- Find the enthalpies of formation for A, B, and C.
- Use Hess’s regulation to calculate the overall enthalpy trade: ΔH_rxn = ΔH_f(C) – ΔH_f(A) – ΔH_f(B)
NEET Sample Questions
Conceptual Questions
| Question | Answer |
|---|---|
| What is the difference between heat and temperature? | Heat is a form of energy, while temperature is a measure of the average kinetic energy of the particles in a system. |
| State the first law of thermodynamics. | Energy can neither be created nor destroyed; it can only be transferred or transformed. |
| Explain the concept of entropy. | Entropy is a measure of the disorder or randomness of a system. |
| What is the difference between an open system and a closed system? | An open system can exchange both matter and energy with its surroundings, while a closed system can exchange only energy. |
| What is the Carnot cycle? | A theoretical cycle that represents the maximum possible efficiency for a heat engine operating between two temperatures. |
Numerical Problems
| Question | Answer |
|---|---|
| Calculate the work done by a gas that expands from a volume of 2 L to 5 L at a constant pressure of 3 atm. | 9 L·atm |
| A 200 g block of copper is heated from 25°C to 100°C. Calculate the heat absorbed by the copper, given that its specific heat capacity is 0.385 J/g·K. | 5775 J |
| A refrigerator has a coefficient of performance of 3. If it removes 1200 J of heat from the cold space, how much work is done by the compressor? | 400 J |
| A heat engine operates between temperatures of 500 K and 300 K. What is its maximum possible efficiency? | 40% |
Tips for Solving Thermodynamics Questions
Common Mistakes to Avoid
- Confusing heat and temperature: Remember that heat is a form of energy, while temperature is a measure of the average kinetic energy of particles.
- Using incorrect units: Always pay attention to units and ensure they are consistent throughout your calculations.
- Forgetting to convert units: If units are not in the same system (e.g., joules and calories), convert them before calculations.
- Neglecting negative signs: Be careful with negative signs, especially when dealing with work done on or by the system.
- Assuming ideal behavior: Remember that real gases may deviate from ideal behavior, especially at high pressures or low temperatures.
- Misapplying equations: Make sure you are using the correct equation for the given process (e.g., isothermal, adiabatic, isobaric).
Strategies for Time Management
- Understand the principles: A strong understanding of the basic principles of thermodynamics will help you solve problems more efficiently.
- Practice regularly: Solve as many practice problems as possible to improve your speed and accuracy.
- Identify key information: Read the problem carefully and identify the given and unknown quantities.
- Choose the right approach: Decide which equations or concepts apply to the problem and plan your solution.
- Check your solutions: After solving a problem, take a moment to review your calculations and ensure your solution is reasonable.
FAQs about Thermodynamics
Q. What is the First Law of Thermodynamics?
Ans: The First Law states that strength can’t be created or destroyed, most effective transformed from one form to another. Mathematically, it’s far expressed as ΔU = Q – W, in which ΔU is the exchange in internal power, Q is warmness brought to the machine, and W is work accomplished by the system.
Q. What is an Isothermal Process?
Ans: An isothermal system happens at a consistent temperature. For best gases, because of this the internal power remains unchanged, and any heat introduced to the gadget is transformed into work.
Q. What is an Adiabatic Process?
Ans: In an adiabatic technique, no warmth is exchanged with the surroundings. The inner strength change is same to the paintings done on or by means of the gadget, main to temperature changes.
Q. What is the Second Law of Thermodynamics?
Ans: The Second Law states that the total entropy of an remoted machine can never decrease over time. It means that natural procedures increase the general entropy of the universe.
Q. What is Entropy?
Ans: Entropy is a degree of the disease or randomness in a device. It quantifies the amount of energy in a bodily machine that isn’t always to be had to do paintings.