Heat and Temperature MCQs 1 to 30 Questions with details Answers.

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 1 to 30

1. Which of the following best describes the common usage of the terms "hot" and "cold"?

A. They are absolute measures of temperature. B. They are always precise and objective. C. They are relative and often subjective. D. They refer only to the transfer of heat.

Correct Answer: C

Explanation: As discussed in Chapter 1, our everyday use of "hot" and "cold" is often imprecise, subjective, and relative to context or personal perception. For instance, lukewarm water might be "too hot" for drinking but "too cold" for tea.

2. What is the scientific term for the degree of hotness or coldness of an object?

A. Heat B. Calorie C. Temperature D. Thermal energy

Correct Answer: C

Explanation: Chapter 1 defines temperature as the degree of hotness, which changes in a continuous manner. A "hotter" body has a higher temperature, while a "colder" body has a lower temperature.

3. Which scientist is credited with one of the earliest successful attempts at measuring the degree of hotness using a gas thermoscope?

A. Joseph Black B. James Joule C. Galileo Galilei D. Robert Boyle

Correct Answer: C

Explanation: Galileo Galilei (around 1610 CE) constructed a gas thermoscope, which expanded or contracted based on temperature changes, making him a pioneer in temperature measurement.

4. What is the normal body temperature of a human on the Celsius scale?

A. 98 °C B. 32 °C C. 37 °C D. 100 °C

Correct Answer: C

Explanation: The text states that the normal temperature of the human body is around 98 °F or 37 °C.

5. If you combine two parts of water, the temperature of the sum of parts is NOT equal to the sum of the temperatures. This indicates that temperature is a(n) ________ property.

A. Extensive B. Additive C. Intensive D. Dependent

Correct Answer: C

Explanation: Temperature is an intensive property, meaning its value does not depend on the amount of the substance. For example, if you combine two mugs of water at the same temperature, the combined water will still be at that same temperature, not double the temperature.

6. When two objects at different initial temperatures are brought into contact, what happens to their temperatures over time?

A. The hotter body gets hotter, and the cooler body gets colder. B. Both bodies maintain their initial temperatures. C. They gradually come to the same temperature. D. The cooler body heats up, but the hotter body's temperature remains constant.

Correct Answer: C

Explanation: Objects in contact gradually come to the same temperature, with heat transferring from the hotter body to the cooler body until thermal equilibrium is reached.

7. What is the term for the state where two bodies in contact have reached the same temperature and no further change in temperature can take place?

A. Thermal transfer B. Heat balance C. Thermal equilibrium D. Temperature saturation

Correct Answer: C

Explanation: The state of achievement of the same temperature by two bodies is called thermal equilibrium, indicating no further temperature change.

8. What is the amount of heat required to increase the temperature of 1 gram of a substance through 1 °C called?

A. Latent heat B. Specific heat C. Thermal capacity D. Calorie

Correct Answer: B

Explanation: The amount of heat required to increase the temperature of 1 g of a substance through 1 °C is called its specific heat (s).

9. What is the specific heat of water in calories per gram per degree Celsius?

A. 0.5 cal/g/°C B. 1 cal/g/°C C. 4.184 cal/g/°C D. 100 cal/g/°C

Correct Answer: B

Explanation: The text states that the amount of heat required to raise the temperature of 1 g of water through 1 °C is called a calorie (cal), meaning the specific heat of water is 1 cal/g/°C.

10. If 100 mL of water at 80 °C and 200 mL of water at 60 °C are mixed, what will be the final temperature of the mixture (assuming no heat loss to surroundings)?

A. 70 °C B. 66.67 °C C. 65 °C D. 73.33 °C

Correct Answer: B

Explanation: Using the formula T = (m1T1 + m2T2) / (m1 + m2), and assuming density of water is 1 g/mL, m1 = 100g, T1 = 80°C, m2 = 200g, T2 = 60°C. So, T = (100*80 + 200*60) / (100 + 200) = (8000 + 12000) / 300 = 20000 / 300 = 66.67 °C.

11. In which direction is heat transferred?

A. From a colder body to a hotter body. B. From a hotter body to a colder body. C. It depends on the specific heat of the bodies. D. It transfers in both directions simultaneously.

Correct Answer: B

Explanation: Heat is always transferred from a body at a higher temperature to a body at a lower temperature.

12. What is the primary mode of heat transfer in solids?

A. Convection B. Radiation C. Conduction D. Evaporation

Correct Answer: C

Explanation: Heat transfer through solids is called conduction, where heat is transferred from one end to another without the overall movement of the material.

13. Which of the following materials is generally considered a good conductor of heat?

A. Glass B. Polyethylene C. Copper D. Air

Correct Answer: C

Explanation: Table 2.1 shows that Copper has a high thermal conductivity (0.99 cal/cm/s/°C) compared to Glass (0.0025) and Polyethylene (0.00006), making it a good conductor.

14. What is the dominant mode of heat transfer in liquids and gases?

A. Conduction B. Radiation C. Convection D. Absorption

Correct Answer: C

Explanation: In liquids and gases, heat transfer primarily occurs through convection, which involves the movement of the fluid itself (e.g., hot water rising and cooler water sinking).

15. How does heat transfer occur in the absence of a medium, such as from the sun to the Earth?

A. Conduction B. Convection C. Radiation D. Evaporation

Correct Answer: C

Explanation: Heat transfer that can occur in the absence of a medium is called radiation. This is how we feel heat from a bonfire or the sun.

16. Why do woollen clothes keep us warm in winter?

A. Wool is a good conductor of heat. B. Wool generates its own heat. C. Wool traps air, which is a poor conductor of heat. D. Wool reflects all incoming cold.

Correct Answer: C

Explanation: Wool has many minute pores that trap air. Since air is a poor conductor of heat, this trapped air acts as an insulator, minimizing heat loss from the body.

17. What is the primary function of a thermos flask?

A. To generate heat. B. To prevent heat transfer. C. To measure temperature accurately. D. To convert heat into work.

Correct Answer: B

Explanation: A thermos flask is designed to minimize all three modes of heat transfer (conduction, convection, and radiation) to keep its contents cool or warm for a long time.

18. Which of the following substances expands the most for a given rise in temperature, assuming equal volumes?

A. Solids B. Liquids C. Gases D. All expand equally.

Correct Answer: C

Explanation: For a given rise in temperature, gases expand significantly more than liquids, and liquids expand more than solids, given equal volumes.

19. What is the term for the process where a solid directly transforms into a gas without passing through a liquid state?

A. Melting B. Evaporation C. Condensation D. Sublimation

Correct Answer: D

Explanation: Sublimation is the process where a solid, like ammonium chloride or camphor, directly converts to a vapor without becoming a liquid.

20. What is the term for the amount of heat per unit mass needed for a substance to change from liquid to vapor at a constant temperature?

A. Specific heat B. Heat capacity C. Latent heat of evaporation D. Boiling point

Correct Answer: C

Explanation: The amount of heat per unit mass needed for the change from liquid to vapor is called the latent heat of evaporation.

21. What anomalous behavior does water exhibit upon freezing compared to most other solids?

A. It contracts upon freezing. B. Its density increases upon freezing. C. It expands upon freezing. D. Its melting point increases with pressure.

Correct Answer: C

Explanation: Water shows anomalous behavior by expanding upon freezing, unlike most other solids which contract. This is why ice floats on water.

22. What is the relationship between pressure and temperature for a fixed mass of an ideal gas at constant volume?

A. Directly proportional B. Inversely proportional C. No direct relationship D. Exponentially related

Correct Answer: A

Explanation: According to Gay-Lussac's Law (implied by Charles' Law and Boyle's Law combined), at constant volume, the pressure of a given mass of an ideal gas is directly proportional to its absolute temperature.

23. When a gas expands, what happens to its thermal energy if it performs work against external pressure?

A. It increases. B. It remains constant. C. It decreases. D. It converts entirely into potential energy.

Correct Answer: C

Explanation: When a gas expands and performs work (e.g., pushing a piston), part of its internal thermal energy is converted into mechanical work, leading to a decrease in its thermal energy and thus its temperature (cooling by expansion).

24. What was the main conclusion from Count Rumford's experiments on heat generation during cannon boring?

A. Heat is a fluid called caloric. B. Heat is a form of energy related to motion. C. Heat can be created and destroyed. D. Specific heat of materials changes during heating.

Correct Answer: B

Explanation: Rumford's experiments demonstrated that an endless supply of heat could be generated by friction, refuting the caloric theory and asserting that heat was related to motion.

25. According to the modern model of matter, what causes the random motion of tiny particles within a substance?

A. External forces only B. Gravitational pull C. Their inherent kinetic energy, related to heat. D. Chemical reactions

Correct Answer: C

Explanation: The modern model postulates that all matter is made of tiny particles in persistent random motion, and this motion is directly related to the substance's heat and temperature.

26. Why does ink spread faster in hot water than in cold water?

A. Hot water has lower density. B. Particles in hot water move more rapidly. C. Cold water has higher viscosity. D. Ink dissolves better in hot water.

Correct Answer: B

Explanation: The text states that "Warmer the water, more rapid is the motion of the particles," leading to faster spreading and mixing of substances like ink or salt.

27. What is the approximate number of particles in 1 mL of a liquid, according to the text?

A. 10¹⁹ B. 10²² C. 10²³ D. 6 x 10²³

Correct Answer: B

Explanation: The text mentions that "Typical numbers per mL are 10¹⁹ for gases, and roughly 10²² for liquids and solids."

28. Why is the average velocity of a large collection of randomly moving particles considered to be zero?

A. Particles are constantly at rest. B. Velocities in opposite directions cancel each other out. C. Particles move too slowly to have a measurable velocity. D. Only the fastest particles contribute to the average.

Correct Answer: B

Explanation: Due to the random motion, for every particle moving in one direction, there's likely another moving in the opposite direction, causing their velocities to cancel out when averaged.

29. What is temperature defined as, in terms of the particulate model of matter?

A. The sum of kinetic energies of all particles. B. A quantity directly proportional to the average kinetic energy of the collection of molecules. C. The rate of collisions between particles. D. The total potential energy of the substance.

Correct Answer: B

Explanation: Temperature (T) is defined as a quantity directly proportional to the average kinetic energy (KEave) of the collection of molecules, with the constant of proportionality being Boltzmann's constant (kB).

30. What is the absolute zero temperature on the Kelvin scale?

A. 0 °C B. -273.15 °C C. 100 K D. The temperature where all internal particulate motion stops.

Correct Answer: D

Explanation: Absolute zero, or zero on the Kelvin scale, is the theoretical temperature at which all internal or particulate motion within a substance ceases.

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