1. The study of thermal properties of matter mainly deals with how matter behaves when there is a change in heat or temperature. What is the most suitable description of this part of physics?
ⓐ. Study of only the motion of bodies under gravity
ⓑ. Study of heat-related changes in matter
ⓒ. Study of electric forces between charged bodies
ⓓ. Study of only the shape of light rays in mirrors
Correct Answer: Study of heat-related changes in matter
Explanation: Thermal properties of matter describe the behaviour of substances when heat is supplied or removed. This includes changes in temperature, size, state, and heat transfer. A metal rod expanding on heating and water boiling are both thermal examples. The topic is not limited to one material or one process. It connects measurable quantities such as \(Q\), \(T\), and \(\Delta T\) with observable changes in matter. The word thermal points to heat-related behaviour, not to mechanics, optics, or electrostatics.
2. A hot cup of tea is kept on a table in a cooler room. The heat transfer mainly occurs because the tea and the surroundings have different values of which quantity?
ⓐ. Heat capacity
ⓑ. Mass
ⓒ. Density
ⓓ. Temperature
Correct Answer: Temperature
Explanation: Heat is energy transferred because of a temperature difference. The tea is at a higher temperature than the surrounding air, so energy flows from the tea to the surroundings. Mass and volume can affect how much heat is involved, but they do not by themselves decide the direction of heat flow. Density is also not the direct cause of heat transfer in this situation. The deciding thermal condition here is the difference between the temperature of the tea and the temperature of the room. When the temperature difference becomes zero, the tendency for net heat transfer stops.
3. Temperature is best understood as a quantity that indicates the thermal state of a body. In ordinary terms, what does it help us decide?
ⓐ. Whether the body has more electric charge
ⓑ. Whether it is hotter or colder
ⓒ. Whether the body is transparent or opaque
ⓓ. Whether the body has larger gravitational force
Correct Answer: Whether it is hotter or colder
Explanation: Temperature tells us about the hotness or coldness of a body in a measurable way. It is a thermal state variable, so it helps compare one body with another. If two bodies are brought near each other thermally, the one at higher temperature tends to lose heat to the one at lower temperature. The amount of matter in the body is not the same thing as its temperature. A small metal spoon may be at a high temperature even if its mass is small. Temperature guides the direction of heat flow, while heat itself is energy transferred during the process.
4. Heat should be treated as:
ⓐ. the same physical quantity as temperature
ⓑ. energy stored permanently inside every hot body
ⓒ. energy transferred due to a temperature difference
ⓓ. a substance that flows like a liquid through matter
Correct Answer: energy transferred due to a temperature difference
Explanation: Heat is not a material substance and it is not identical to temperature. It is energy in transfer when a temperature difference exists. A body may have internal energy, but heat refers to the energy crossing a boundary because one part is hotter than another. This is why we speak of heat supplied to water or heat lost by a cooling object. The direction of transfer is usually from higher temperature to lower temperature. Treating heat as something stored like a fluid hides the role of temperature difference in thermal processes.
5. A laboratory note uses \(Q\), \(T\), and \(\Delta T\) in a heating observation. What is the best interpretation of these symbols?
ⓐ. \(Q\) is heat, \(T\) is temperature, and \(\Delta T\) is change in temperature
ⓑ. \(Q\) is mass, \(T\) is heat capacity, and \(\Delta T\) is latent heat
ⓒ. \(Q\) is temperature, \(T\) is heat, and \(\Delta T\) is change in temperature
ⓓ. \(Q\) is volume, \(T\) is density, and \(\Delta T\) is pressure
Correct Answer: \(Q\) is heat, \(T\) is temperature, and \(\Delta T\) is change in temperature
Explanation: The symbol \(Q\) commonly represents heat transferred. The symbol \(T\) represents temperature, usually measured in \(\text{K}\) in formula-based work. The notation \(\Delta T\) means the change in temperature, not the absolute temperature itself. These symbols appear repeatedly in heating, cooling, calorimetry, and heat-transfer relations. Confusing \(T\) with \(\Delta T\) can lead to wrong formula use later. In thermal calculations, the symbol tells whether the problem needs a temperature value or a temperature change.
6. The SI unit used to measure heat is:
ⓐ. \(\text{K}\)
ⓑ. \(\text{J}\)
ⓒ. \(\text{m}\)
ⓓ. \(\text{kg}\)
Correct Answer: \(\text{J}\)
Explanation: Heat is a form of energy transfer, so its SI unit is the joule, written as \(\text{J}\). The kelvin, written as \(\text{K}\), is used for temperature. The metre, written as \(\text{m}\), is a unit of length, while kilogram, written as \(\text{kg}\), is a unit of mass. This unit distinction is important because heat and temperature are related but not the same quantity. A body can undergo a temperature rise when heat is supplied, but the two quantities are measured in different units. The unit \(\text{J}\) connects heat with the broader idea of energy.
7. Temperature may commonly be expressed in:
ⓐ. \(\text{kg}\) or \(\text{m}\)
ⓑ. \(\text{kg m}^{-3}\) or \(\text{W}\)
ⓒ. \(\text{J}\) or \(\text{W}\)
ⓓ. \(\text{K}\) or \({}^\circ\text{C}\)
Correct Answer: \(\text{K}\) or \({}^\circ\text{C}\)
Explanation: Temperature is measured on scales such as kelvin and Celsius. The SI unit of temperature is \(\text{K}\), while \({}^\circ\text{C}\) is widely used in everyday and laboratory readings. The joule, \(\text{J}\), measures energy or heat, not temperature. The watt, \(\text{W}\), measures power or rate of energy transfer. The unit \(\text{kg m}^{-3}\) is used for density. A temperature reading must therefore carry a temperature unit, not an energy or density unit.
8. A metal spoon has one end dipped in hot water, and after some time its other end also becomes warm. This observation is mainly connected with:
ⓐ. formation of a vacuum
ⓑ. decrease of mass in the spoon
ⓒ. change of state only
ⓓ. heat transfer through matter
Correct Answer: heat transfer through matter
Explanation: The spoon becomes warm because heat is transferred from the hot end toward the cooler end. This is a thermal process because it is driven by a temperature difference within the spoon. The spoon need not melt or boil for heat transfer to occur. Its mass does not decrease merely because heat moves through it. The example is a simple early indication that heat can pass through matter. The later detailed name for this process in solids is conduction, but the basic idea here is heat transfer caused by unequal temperature.
9. In thermal expansion, a solid rod generally becomes longer when heated because:
ⓐ. its temperature must remain constant during heating
ⓑ. its average molecular separation increases
ⓒ. its mass increases during heating
ⓓ. heat changes into extra material inside the rod
Correct Answer: its average molecular separation increases
Explanation: Most solids expand on heating because their particles vibrate more vigorously and their average separation increases slightly. The rod does not become longer because new matter is created. Its mass remains essentially the same during ordinary heating. Temperature generally changes during heating unless a phase change or special condition is involved. Thermal expansion is therefore a size change caused by thermal agitation at the microscopic level. This idea later leads to relations involving \(\alpha\), \(\beta\), and \(\gamma\).
10. A beaker of water is heated until it starts boiling. The observation belongs most closely to which thermal idea?
ⓐ. Electric charging by friction
ⓑ. Reflection of sound
ⓒ. Change of state
ⓓ. Magnetic induction
Correct Answer: Change of state
Explanation: Boiling changes water from the liquid state to the gaseous state. This is a thermal process because heat supplied to the water is involved in changing the state. The process is different from simple warming, where temperature changes without a change of state. Reflection of sound and electric charging are not thermal changes of matter. Magnetic induction also belongs to a different branch of physics. Boiling is an early example showing that heat can change the physical state of a substance.
11. Study the table and select the row that matches the quantity with its usual unit.
| Row | Quantity | Usual unit |
|---|
| P | Heat \(Q\) | \(\text{J}\) |
| Q | Temperature \(T\) | \(\text{kg}\) |
| R | Mass \(m\) | \(\text{K}\) |
| S | Power | \(\text{m}\) |
ⓐ. Row R only
ⓑ. Row Q only
ⓒ. Row S only
ⓓ. Row P only
Correct Answer: Row P only
Explanation: Heat \(Q\) is energy transferred due to a temperature difference, so it is measured in joule, \(\text{J}\). Temperature \(T\) is measured in \(\text{K}\) or \({}^\circ\text{C}\), not in \(\text{kg}\). Mass \(m\) is measured in \(\text{kg}\), not in \(\text{K}\). Power is measured in watt, \(\text{W}\), not in metre, \(\text{m}\). Row P is the only row in the table where the physical quantity and unit are paired properly. Unit matching is useful because many thermal formulas combine energy, mass, and temperature change.
12. A colder steel cup and warmer water are brought into contact. Before they reach the same thermal condition, the natural heat transfer is expected to be:
ⓐ. from the denser substance to the less dense substance always
ⓑ. from the smaller mass to the larger mass always
ⓒ. from the steel cup to the warmer water
ⓓ. from the warmer water to the colder steel cup
Correct Answer: from the warmer water to the colder steel cup
Explanation: Heat flows naturally from a body at higher temperature to a body at lower temperature. In this case the water is warmer, so it tends to lose heat to the colder steel cup. The direction is not decided only by mass or density. A smaller body can be hotter than a larger body, and a denser body is not necessarily the one that loses heat. Temperature is the quantity that decides the direction of natural heat transfer. Mass and material affect the amount of temperature change produced by a given heat transfer.
13. The statement “a body contains heat” is not a careful physics statement because heat means:
ⓐ. the same thing as the Celsius reading of the body
ⓑ. the total mass of all molecules in the body
ⓒ. the colour change produced by heating
ⓓ. energy transfer due to temperature difference
Correct Answer: energy transfer due to temperature difference
Explanation: In careful thermal physics, heat refers to energy being transferred, not to something simply stored in a body. A body possesses internal energy, but heat is named when energy crosses from one system to another because of a temperature difference. The Celsius reading describes temperature, not heat. Colour change may occur in some heating situations, but it is not the definition of heat. Saying that a body “contains heat” can blur the distinction between internal energy and energy transfer. The useful wording is that heat is supplied to or removed from a body.
14. Match the symbols with the ideas they commonly represent in thermal physics.
| Symbol | Idea |
|---|
| P. \(m\) | 1. Mass of a body |
| Q. \(c\) | 2. Specific heat capacity |
| R. \(C\) | 3. Heat capacity of a body |
| S. \(L\) | 4. Latent heat |
ⓐ. P-2, Q-1, R-3, S-4
ⓑ. P-1, Q-2, R-3, S-4
ⓒ. P-4, Q-2, R-3, S-1
ⓓ. P-1, Q-3, R-2, S-4
Correct Answer: P-1, Q-2, R-3, S-4
Explanation: The symbol \(m\) usually represents mass. The small letter \(c\) is used for specific heat capacity, while the capital letter \(C\) is used for heat capacity of a body. The symbol \(L\) represents latent heat in phase-change problems. The distinction between \(c\) and \(C\) is important because \(c\) is a material property per unit mass, while \(C\) belongs to a particular body. The symbol \(L\) is used when heat is involved in changing state rather than simply changing temperature.
15. A simple heating record says that \(500\,\text{J}\) of heat is supplied to a small metal block. The value \(500\,\text{J}\) describes:
ⓐ. the energy transferred to the block
ⓑ. the mass of the block
ⓒ. the temperature of the block
ⓓ. the coefficient of expansion of the block
Correct Answer: the energy transferred to the block
Explanation: The unit \(\text{J}\) identifies the quantity as energy, so \(500\,\text{J}\) describes heat supplied. It does not directly give the temperature because temperature must be expressed in \(\text{K}\) or \({}^\circ\text{C}\). The same amount of heat can produce different temperature changes in different bodies depending on their mass and material. It is also not a coefficient of expansion, since expansion coefficients have unit \(\text{K}^{-1}\). This example separates heat supplied from temperature reached. The numerical value of heat alone does not tell the final thermal state unless more information is known.
16. A graph is described with temperature \(T\) on the vertical axis and time on the horizontal axis while a body is heated steadily. What does a rising part of the graph most simply suggest?
ⓐ. The body’s mass is increasing with time
ⓑ. The body has stopped receiving heat
ⓒ. The body’s temperature is measured in \(\text{J}\)
ⓓ. The body’s temperature is increasing with time
Correct Answer: The body’s temperature is increasing with time
Explanation: If \(T\) is plotted on the vertical axis, a rising graph means the temperature value is increasing as time passes. This does not mean the mass of the body is increasing. A body may still be receiving heat during such a rise, depending on the heating arrangement. Temperature is not measured in \(\text{J}\); it is measured in \(\text{K}\) or \({}^\circ\text{C}\). Graph interpretation begins by identifying what each axis represents. Here the vertical rise is a change in thermal state, not a direct measurement of heat in joules.
17. Two objects are at the same temperature, but one has much larger mass. What can be concluded from this information alone?
ⓐ. Heat must flow from the larger object to the smaller object
ⓑ. The larger object must have lower temperature
ⓒ. Both objects must contain the same amount of heat
ⓓ. Same temperature, not necessarily same thermal energy
Correct Answer: Same temperature, not necessarily same thermal energy
Explanation: Equal temperature means the two objects have the same thermal state reading on a temperature scale. It does not mean that the objects have the same amount of internal energy or the same heat capacity. A larger object can involve more matter and may require more heat for the same temperature change. Heat flow is not decided by mass alone; it depends on temperature difference. If the temperatures are equal, there is no natural direction of heat flow based only on temperature. This distinction prevents the common confusion that same temperature means same heat content.
18. A thermal process is observed in each case below. Select the case in which heat transfer is most clearly linked to a temperature difference.
ⓐ. A stone falls freely near Earth
ⓑ. A book remains at rest on a table
ⓒ. A hot metal lid warms cooler air
ⓓ. A compass needle aligns in a magnetic field
Correct Answer: A hot metal lid warms cooler air
Explanation: A hot metal lid and cooler surrounding air have different temperatures, so heat can transfer from the lid to the air. This is a thermal situation because the process is driven by a temperature difference. A book resting on a table is mainly a mechanical equilibrium situation. A falling stone involves gravitational motion, and a compass needle involves magnetism. The option with the hot lid directly shows energy transfer due to thermal contact with a cooler surrounding. Temperature difference is the key condition that makes the example thermal.
19. A metal block at \(80^\circ\text{C}\) is kept in contact with another block at \(30^\circ\text{C}\). Before they reach the same temperature, the direction of natural heat flow is:
ⓐ. from the heavier block to the lighter block always
ⓑ. from the block with larger volume to the block with smaller volume always
ⓒ. from the \(30^\circ\text{C}\) block to the \(80^\circ\text{C}\) block
ⓓ. from the \(80^\circ\text{C}\) block to the \(30^\circ\text{C}\) block
Correct Answer: from the \(80^\circ\text{C}\) block to the \(30^\circ\text{C}\) block
Explanation: Natural heat transfer takes place from a body at higher temperature to a body at lower temperature. Here, the block at \(80^\circ\text{C}\) is hotter than the block at \(30^\circ\text{C}\). The mass or volume of the blocks can affect how their temperatures change, but it does not decide the natural direction of heat flow by itself. The temperature difference is the immediate cause of heat transfer in this situation. Heat transfer continues until both bodies reach the same temperature, if they are otherwise isolated. A larger body is not automatically the heat giver unless it is at the higher temperature.
20. A notebook entry says: “The heat supplied to a body is \(Q=1200\,\text{J}\), and its temperature rises by \(\Delta T=6\,\text{K}\).” In this entry, the symbol \(\Delta T\) represents:
ⓐ. the body’s temperature change
ⓑ. the initial temperature of the body
ⓒ. the final temperature of the body
ⓓ. the heat transferred to the body
Correct Answer: the body’s temperature change
Explanation: The symbol \(\Delta T\) means change in temperature. It is not the same as the initial temperature or final temperature separately. If the body warms, \(\Delta T\) is commonly written as \(T_{\text{final}}-T_{\text{initial}}\). The value \(Q=1200\,\text{J}\) represents heat transferred, not temperature change. This distinction becomes important in formulas such as \(Q=mc\Delta T\), where the temperature interval is used. A calculation that uses absolute temperature in place of \(\Delta T\) may give a physically wrong heat value.
