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| Heat and Temperature MCQs |
🔥 Heat and Temperature MCQs – Universal Practice Set for All Exams
This carefully curated collection of Heat and Temperature Multiple-Choice Questions (MCQs) is designed to serve learners and aspirants across every major exam format worldwide. From grasping basic thermal concepts to tackling advanced thermodynamics, these questions help you master topics such as heat transfer, temperature scales, specific heat, thermal expansion, and real-world applications.
Ideal for:
- School-level Science Exams (middle & high-school physics)
- College & University Physics Courses
- Board Examinations (CBSE, ICSE, State Boards, IB, IGCSE, etc.)
- Government & Competitive Exams (UPSC, MPSC, SSC, Railways, Defence, etc.)
- Medical & Engineering Entrances (NEET, JEE, CUET, GATE, etc.)
- International Assessments (SAT, GRE, global Olympiads, and professional certifications)
Every MCQ is paired with a concise, concept-focused explanation, ensuring thorough understanding and quick revision. Whether you are a student preparing for classroom tests, a graduate gearing up for professional licensure, or an international candidate seeking a competitive edge, this practice set offers a one-stop solution for mastering Heat and Temperature concepts.
Heat and Temperature MCQs
31. What happens to the kinetic energy of molecules in a substance as its temperature increases?
Correct Answer: C
Explanation: Temperature is a measure of the average kinetic energy of the particles in a substance. As temperature increases, the particles move faster, and their average kinetic energy increases.
32. In the particulate model of matter, what represents the internal energy of a substance?
Correct Answer: C
Explanation: The internal energy of a substance is the sum of the kinetic energy (due to motion) and potential energy (due to intermolecular forces) of its constituent particles.
33. What is the process called when a liquid turns into a solid upon cooling?
Correct Answer: C
Explanation: Freezing is the process where a liquid changes its state to a solid, typically by losing heat and reaching its freezing point.
34. Why does the temperature of a substance remain constant during a phase change (e.g., melting or boiling), even though heat is being added?
Correct Answer: B
Explanation: During a phase change, the added heat, known as latent heat, is used to overcome the intermolecular forces and change the arrangement of particles, rather than increasing their kinetic energy (and thus temperature).
35. What is the unit of specific heat in the SI system?
Correct Answer: B
Explanation: In the SI system, the unit of specific heat is Joules per kilogram per Kelvin (J/kg·K) or Joules per kilogram per degree Celsius (J/kg·°C).
36. Which of the following has the highest specific heat capacity?
Correct Answer: C
Explanation: Water has a remarkably high specific heat capacity (approximately 4.184 J/g·°C or 1 cal/g·°C), meaning it requires a large amount of heat to change its temperature, compared to most other common substances.
37. If a metal spoon is placed in a cup of hot coffee, how is heat primarily transferred from the coffee to the spoon?
Correct Answer: C
Explanation: Heat transfer from the hot coffee to the solid spoon occurs primarily through conduction, as the molecules in direct contact transfer energy to adjacent molecules.
38. What is a 'sea breeze' an example of?
Correct Answer: B
Explanation: A sea breeze is a classic example of convection. During the day, land heats up faster than the sea, causing the air above the land to rise. Cooler air from the sea then moves in to replace it, creating a breeze.
39. Why are houses in hot climates often painted white?
Correct Answer: B
Explanation: White surfaces are good reflectors of heat radiation and poor absorbers. Painting houses white helps to reflect sunlight and keep the interior cooler.
40. What is the principle behind a bimetallic strip used in thermostats?
Correct Answer: C
Explanation: A bimetallic strip works on the principle of thermal expansion. Two different metals with different coefficients of thermal expansion are bonded together. When heated, they expand by different amounts, causing the strip to bend.
41. Which of the following statements about thermal expansion is true?
Correct Answer: C
Explanation: Generally, for the same temperature change and initial volume, gases expand the most, followed by liquids, and then solids.
42. What is the effect of increasing pressure on the boiling point of a liquid?
Correct Answer: B
Explanation: An increase in external pressure makes it harder for liquid molecules to escape into the gas phase, thus requiring a higher temperature (and more kinetic energy) for boiling to occur.
43. What is the effect of impurities on the melting point of a solid?
Correct Answer: B
Explanation: Impurities generally disrupt the crystal lattice structure of a solid, making it easier for the substance to melt at a lower temperature.
44. Why do water pipes burst in extremely cold weather?
Correct Answer: B
Explanation: Water exhibits anomalous expansion; it expands when it freezes into ice. If water freezes inside pipes, the expansion can exert immense pressure, causing the pipes to burst.
45. What is the relationship between volume and temperature for a fixed mass of an ideal gas at constant pressure?
Correct Answer: B
Explanation: According to Charles's Law, for a fixed mass of an ideal gas at constant pressure, the volume is directly proportional to its absolute temperature.
46. What is the relationship between pressure and volume for a fixed mass of an ideal gas at constant temperature?
Correct Answer: B
Explanation: According to Boyle's Law, for a fixed mass of an ideal gas at constant temperature, the pressure is inversely proportional to its volume.
47. What is the term for the heat absorbed or released during a phase change at constant temperature?
Correct Answer: C
Explanation: Latent heat is the heat absorbed or released during a phase transition (e.g., melting, freezing, boiling, condensation) without a change in temperature.
48. Which of the following is a good example of heat transfer by radiation?
Correct Answer: B
Explanation: Feeling warmth from a fireplace across the room is primarily due to thermal radiation, which travels through electromagnetic waves and does not require a medium.
49. Why does a desert cool down much faster at night compared to a coastal area?
Correct Answer: B
Explanation: Sand has a much lower specific heat capacity than water. This means sand heats up quickly during the day and cools down quickly at night, while water (and coastal areas) retains heat for longer.
50. What happens to the density of most substances when they are heated?
Correct Answer: B
Explanation: Most substances expand when heated, meaning their volume increases while their mass remains constant. Since density = mass/volume, an increase in volume leads to a decrease in density.
51. What is the phenomenon where a liquid turns into a gas at a temperature below its boiling point?
Correct Answer: C
Explanation: Evaporation is the process by which a liquid changes into a gas (vapor) at a temperature below its boiling point, occurring primarily at the surface of the liquid.
52. How does a refrigerator cool its contents?
Correct Answer: B
Explanation: A refrigerator works by transferring heat from its inside (where it's cold) to the outside (where it's warmer), effectively removing heat from the food and air inside.
53. What is the purpose of a cooling fan in electronic devices?
Correct Answer: C
Explanation: Electronic components generate heat during operation. A cooling fan helps to dissipate this excess heat, preventing overheating and ensuring optimal performance and longevity of the device.
54. Which state of matter has the strongest intermolecular forces?
Correct Answer: A
Explanation: In solids, particles are tightly packed and held in fixed positions by strong intermolecular forces, giving solids a definite shape and volume.
55. What is the term for the energy that flows from a hotter object to a colder object due to a temperature difference?
Correct Answer: C
Explanation: Heat is defined as the energy transferred between objects (or systems) due to a temperature difference.
56. What happens to the potential energy between molecules when a substance melts?
Correct Answer: B
Explanation: During melting, the bonds holding particles in a fixed solid structure are partially overcome. The energy absorbed (latent heat of fusion) increases the potential energy between molecules, allowing them to move more freely as a liquid.
57. Why is it generally advised to fill a car radiator with water rather than another liquid like alcohol?
Correct Answer: C
Explanation: Water's high specific heat capacity allows it to absorb a large amount of heat from the engine without a significant rise in its own temperature, making it an excellent coolant.
58. What is the process of heat transfer through the movement of fluids (liquids or gases)?
Correct Answer: C
Explanation: Convection is the transfer of heat by the actual movement of the heated fluid itself.
59. Which type of thermometer uses the expansion of a liquid (like mercury or alcohol) to measure temperature?
Correct Answer: B
Explanation: Liquid-in-glass thermometers rely on the principle that liquids expand predictably when heated. As the liquid expands, it rises in a narrow capillary tube, indicating the temperature.
60. What is the term for the temperature at which a liquid starts to boil and turn into a gas at a given pressure?
Correct Answer: D
Explanation: The boiling point is the temperature at which the vapor pressure of a liquid equals the external pressure, causing the liquid to rapidly change into a gas throughout the bulk of the liquid.
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