# Thermodynamics MCQ Mechanical Engineering

50 Questions 30 Mins

Thermodynamics is the study of heat and energy. It is a physical science that covers a wide range of topics, from the behavior of gases to the workings of engines. . Thermodynamics is a branch of physics that deals with the relationship between heat and energy. The word "thermodynamics" comes from the Greek words for "heat" and "power." Thermodynamics is a very old science; its roots can be traced back to the early 19th century.

Thermodynamics is divided into three main branches:

Classical thermodynamics, statistical thermodynamics, and kinetic theory. Classical thermodynamics deals with the behavior of gases and other macroscopic systems. Statistical thermodynamics deals with the behavior of molecules and other microscopic particles.

Thermodynamic principles are used in a variety of fields, such as engineering, biology, and chemistry. Thermodynamic concepts are also important in the study of phase transitions, such as the melting of ice or the boiling of water.

#### Wrapping Up

In addition, thermodynamics is used to understand a wide range of phenomena, from the behavior of black holes to the properties of materials. Thermodynamics is a vital part of many scientific disciplines, and it plays a key role in our understanding of the universe.

Following are some of the multiple choice questions on the Thermodynamics with answers that will help the students in developing their knowledge.

## Thermodynamics MCQ

### 1. Heat is

• hot
• the energy that is transferred between objects because of a temperaturedifference
• the quantity measure from the average kinetic energy of vibrating molecules in a substance
• none of the above

### 2. Which of the following has the highest calorific value?

• Anthracite coal
• Bituminous coal
• Peat
• Lignite

### 3. How does a refrigerator work?

• Moves heat from inside the fridge to the room
• Blows cold air into the fridge
• Uses convection cells
• It generates cold air

### 4. Mixture of ice and water form a

• Closed system
• Open system
• Isolated system
• Heterogeneous system

### 5. Addition of heat at constant pressure to a gas results in

• Raising its temperature
• Raising its pressure
• Raising its volume
• Raising its temperature and doing external work

### 6. Warm air rises and cold air sinks demonstrates what?

• conduction
• convection
• refrigeration

### 7. Define Exothermic

• Energy is released; ΔH is negative; Going from Gas to Liquid, Liquid to Solid
• Energy is absorbed; ΔH is positive; Going from Gas to Liquid, Liquid to Solid
• Energy is released; ΔH is positive; Going from Solid to Liquid, Liquid to Gas
• Energy is absorbed; ΔH is negative; Going from Gas to Liquid, Liquid to Solid

• oven mitt
• curling iron
• iron skillet
• copper pipe

### 9. Which of the following gas has the highest calorific value?

• Coal gas
• Producer gas
• Mond gas
• Blast furnace gas

### 10. The absolute zero pressure can be attained at a temperature of

• 0°C
• -273°C
• 273 K
• None of these

### 11. For an adiabatic process, which of the following statements is correct?

• Work, heat, and internal energy all undergo changes.
• ﻿ Work and heat balance each other, so that there is no change in internal energy.
• No energy is transferred as heat; internal energy change is due to work.
• No work is done; internal energy change is due to heat.

### 12. The first law of thermodynamics is a restatement of the

• Zeroth law of thermodynamics
• law of heat addition
• principle of entropy
• conservation of energy

• 56,484 J
• 339,000 J
• 395,484 J
• 385,484 J

### 14. What happens to particles when they are heated?

• They speed up and spread out
• They slow down and compress
• They stop moving
• They move closer together and speed up

### 15. Which is an example of decreasing entropy in a closed system?

• Boiling water
• Freezing water
• Cells in a body coming together
• Ice melting

### 16. Which statement is true about the ENTROPY?

• Entropy refers to DISORDER, the unusable energy that escapes a system.
• Entropy refers to the balance of temperature among two or more systems.
• Entropy refers to the average kinetic energy of the molecules.
• Entropy refers to the inability to destroy or create energy.

• 25 g
• 30 g
• 20 g
• 50 g

• 1/4
• Zero
• 1/5
• 2

### 19. Water has a specific heat of 4184 J/KgºC. Wood has a specific heat of 1760 J/KgºC. What material needs more energy to raise the temperature 1ºC

• Wood
• Water
• Both are the same
• none of the above

### 20. In closed cycle gas turbine, the air is compressed

• Isothermally
• Isentropically
• Polytropically
• None of these

### 21. If a gas is heated against a pressure, keeping the volume constant, then work done will be equal to

• +ve
• -ve
• Zero
• Anywhere between zero and infinity

### 22. How are solids different from liquids?

• particles in solids are moving freely around each other.
• particles in solids have no motion.
• particles in solids are vibrating in place.
• particles in solids have more motion than in liquids

### 23. Carbonization of coal consists of

• Drying and crushing the coal to a fine powder
• Moulding the finely ground coal under pressure with or without a binding material
• Heating the wood with a limited supply of air to temperature not less than 280°C
• None of the above

• 1
• 1.4
• 1.45
• 2.3

### 25. Which of the following is not a scale used to measure temperature?

• Fahrenheit
• Celsius
• Kelvin
• Thermodynamic

• True
• False

### 27. What happens on a molecular level when heat is removed from an object?

• the temperature decreases and the molecules move faster
• the temperature increases and the molecules move slower
• the temperature increases and the molecules molecules move faster
• the temperature decreases and the molecules move slower

### 28. Transfer of heat in a gas or liquid by the motion of particles in the heated fluid

• conduction
• convection
• none of the above

• Newton
• Pascal
• Erg
• Watt

### 30. When applying the first law of thermodynamics to a system, when is heat a positive quantity?

• when the system does work
• when the system has work done on it
• when the system absorbs heat
• when the system loses heat

• insulation.
• Conduction
• Convection

• heat
• cold
• energy
• temperature

• Zeroth
• First
• Second
• Third

### 34. DON'T RUSH, YOU HAVE TIME.Frying an egg on a skillet. Referring to the egg, would the Enthalpy change be positive or negative?

• Skillet is absorbing heat energy from the egg. Absorbing energy is Endothermic. Endothermic has a positive Enthalpy
• Egg absorbing heat energy from the skillet. Absorbing energy is Endothermic. Endothermic has a positive Enthalpy
• Egg absorbing heat energy from the skillet. Releasing energy is Exothermic. Exothermic has a positive Enthalpy
• Egg absorbing heat energy from the skillet. Releasing energy is Exothermic. Exothermic has a negative Enthalpy

• temperature
• conduction
• heat

### 36. DON'T RUSH, YOU HAVE TIME. Water droplets condensing on the inside of a window on a cold day. Is this process exothermic or endothermic?

• Gases condense to form liquids. Gases are moving faster than liquids, the air around the window has a higher temperature/kinetic energy. Releasing energy to get water droplets, which is is Exothermic
• Gases condense to form liquids. Gases are moving faster than liquids, the air around the window has a higher temperature/kinetic energy. Releasing energy to get water droplets, which is is Endothermic
• Gases condense to form liquids. Gases particles are moving slower than liquids. Releasing energy to get water droplets, which is is Endothermic
• Gases condense to form liquids. Gases particles are moving slower than liquids. Releasing energy to get water droplets, which is is Exothermic

### 37. Exothermic reactions...

• Absorb energy
• Release energy
• Release Color
• Absorb Color

• conduction
• convection
• insulation

### 39. When you place the metal in boiling water, heat flows from the _________ to the _______.

• metal to the boiling water
• bottom of the metal to the top half of the metal
• bottom of the water to the top of the water
• boiling water to the metal

### 40. Stored energy that results from the position or shape of an object is called...

• Thermal
• Potential
• Kinetic
• Gravitational

• -80,371.2 J
• 44,938.6 J
• 80,371.2 J
• 112,575.9 K

### 42. If I heat up 2 pans of water one has 100 mL in it and one has 1000mL. Which one heats up the fastest?

• 100 mL
• 1000 mL
• They both heat up at the same speed
• They cool down.

• 200 J
• 400 J
• 33,400 J
• 2,000,000 J

### 44. Particles (molecules) in a ______________________ have less energy than the other states of matter.

• gas
• solid
• liquid
• none of the above

• 2
• 4
• 8
• 16

### 46. For the same maximum pressure and temperature,

• Otto cycle is more efficient than Diesel cycle
• Diesel cycle is more efficient than Otto cycle
• Dual cycle is more efficient than Otto and Diesel cycles
• Dual cycle is less efficient than Otto and Diesel cycles

### 47. Molecular volume of any perfect gas at 600 × 103 N/m² and 27°C will be

• 4.17 m3/kg mol
• 400 m3/kg mol
• 0.15 m3/kg mol
• 41.7 m3/kg mol

### 48. An actual engine is to be designed having same efficiency as the Carnot cycle. Such a proposition is

• Feasible
• Impossible
• Possible
• Possible, but with lot of sophistications

### 49. What does the "U" stand for the formula ∆U = Q + W

• Heat
• Temperature
• Work
• Internal energy

• Endothermic
• Exothermic