📘 Chapter 7: Thermal Properties of Matter – Exercise Short Answer Questions
Prepared by Muhammad Tayyab, Subject Specialist Physics, Govt Christian High School Daska. Based on PECTAA 2026 syllabus (National Curriculum 2023).
📖 What's Inside: This section covers exercise short answer questions from Chapter 7 Thermal Properties of Matter including Kinetic Molecular Theory, Temperature, Heat vs Internal Energy, Thermometers, Thermometric Properties, Temperature Scales, Sensitivity, Linearity, and Heat Flow. Each question is presented with a detailed answer as per the official PECTAA 2026 Physics curriculum. Perfect for Punjab Boards (Lahore, Gujranwala, Multan, etc.) and all BISE boards across Pakistan.
📚 Related Resources – Chapter 7: Thermal Properties of Matter
📋 Exercise Short Qs
📝 Short Qs
📖 Comprehensive Qs
🔢 Numerical Problems
✅ MCQs
✏️ Constructed Response
Thermal Properties of Matter covers temperature, heat, thermometers, temperature scales, and kinetic molecular theory.
📖 Exercise Short Answer Questions & Answers (PECTAA 2026)
7.1 Why solids have a fixed volume and shape according to particle theory of matter?
Answer:
In case of solids, the intermolecular forces are so strong that they keep the molecules bound. So, the molecules are held at fixed positions but still they show vibrational motion about their fixed points. This is why, the solids have a definite shape and a definite volume.
✅ Strong intermolecular forces → molecules held at fixed positions → definite shape and volume
7.2 What are the reasons that gases have neither a fixed volume nor a fixed shape?
Answer:
Gas molecules are relatively far away from one and another. Due to which, gas neither possesses a definite volume nor a definite shape.
✅ Molecules far apart → no fixed volume or shape
7.3 Compare the spacing of molecules in the solid, liquid and gaseous state.
Answer:
In solids, the molecules are held at fixed positions due to strong intermolecular forces.
In liquids, the intermolecular force is weaker and the molecules can slide over each other.
Gas molecules are relatively far away from one and another.
✅ Solid: fixed positions | Liquid: slide over each other | Gas: far apart
7.4 What is the effect of raising the temperature of a liquid?
Answer:
When a substance is heated, its temperature rises and its molecular motion becomes more vigorous which increases the kinetic energy of the molecules.
Thus, the temperature of the substance depends upon the average kinetic energy of its molecules.
✅ Heating → more molecular motion → increased kinetic energy
7.5 What is meant by temperature of a body?
Answer:
Temperature of a body is defined as degree of its hotness or coldness.
✅ Degree of hotness or coldness
7.6 Define heat as 'energy in transit'.
Answer:
Heat is the energy which is transferred from one object to another due to difference of temperature between the two bodies.
✅ Heat = energy in transit due to temperature difference
7.7 What is meant by thermometric property of a substance? Enlist some thermometric properties.
Answer:
A thermometric property is a property of a substance which changes appreciably with the change of temperature.
Some basic thermometric properties for a material suitable to construct a thermometer are the following:
- (i) It is a good conductor of heat.
- (ii) It gives quick response to temperature changes.
- (iii) It has uniform thermal expansion.
- (iv) It has high boiling point.
- (v) It has low freezing point.
- (vi) It has large expansivity (low specific heat capacity).
- (vii) It does not wet glass.
- (viii) It does not vapourize.
- (ix) It is visible.
OR
Some thermometric properties are:
- (i) Pressure of a given mass of gas, used in gas thermometers.
- (ii) Resistance of a given length of wire, used in platinum resistance thermometer.
- (iii) Thermo-electric current, used in a thermocouple.
✅ Property that changes with temperature | Examples: expansion, pressure, resistance
7.8 State the main scales used for the measurement of temperature.
Answer:
The three different scales of temperature are:
- (i) Celsius or centigrade scale
- (ii) Fahrenheit scale
- (iii) Kelvin scale
✅ Celsius, Fahrenheit, Kelvin
7.9 What is meant by sensitivity of a thermometer?
Answer:
Sensitivity of a thermometer refers to its ability to detect small changes in the temperature of an object.
✅ Ability to detect small temperature changes
7.10 What do you mean by the linearity of a thermometer?
Answer:
Linearity refers to a direct proportional relationship between the temperature and scale reading across entire range of measurement.
✅ Direct proportional relationship between temperature and scale reading
7.11 What makes the scale reading of a thermometer accurate?
Answer:
A good linear thermometer should measure equal increments on the scale corresponding to equal change in the temperature. It means that marking on the scale should be evenly spaced over the whole range.
✅ Equal increments for equal temperature changes | Evenly spaced markings
7.12 What does determine the direction of heat flow?
Answer:
Temperature determines the direction of flow of thermal energy. Thermal energy is transferred from one object to another due to the temperature difference of the two bodies.
✅ Temperature difference determines direction of heat flow
7.13 Distinguish between the heat and internal energy.
Answer:
Heat: Heat is the energy which is transferred from one object to another due to difference of temperature between the two bodies.
Internal energy: The sum of kinetic and potential energies of the molecules of an object is called its internal energy.
The word heat is used only when referring to the energy actually in transit from hot to cold body.
✅ Heat = energy in transit | Internal energy = sum of KE + PE of molecules
7.14 When you touch a cold surface, does cold travel from the surface to your hand or does energy travel from your hand to cold surface?
Answer:
Thermal energy is transferred from one object to another due to the temperature difference of the two bodies. Therefore, energy travels from your hand to the cold surface.
✅ Energy travels from hand (hotter) to cold surface (colder)
7.15 Can you feel your fever by touching your own forehead? Explain.
Answer:
Our sense of touch can tell us whether an object is hot or cold, but we cannot measure the actual temperature of the body just by touching it. For the exact measurement of temperature, we require an instrument called a thermometer.
✅ Touch gives rough idea only | Thermometer needed for exact measurement
📐 Key Concepts – Thermal Properties of Matter (Exercise Short Questions)
Temperature: Degree of hotness or coldness
Heat: Energy in transit due to temperature difference
Internal Energy: Sum of kinetic and potential energies of molecules
Temperature Scales: Celsius (\(^\circ C\)), Fahrenheit (\(^\circ F\)), Kelvin (K)
Sensitivity: Ability to detect small temperature changes
Linearity: Proportional relationship between temperature and scale reading
💡 Exam Tip:
For exercise short questions, write concise and accurate answers. Use definitions, formulas, and examples where required. These questions test your understanding of fundamental concepts like kinetic molecular theory, temperature, heat vs internal energy, thermometric properties, and temperature scales. These questions follow the PECTAA 2026 pattern and are prepared by Subject Specialist Muhammad Tayyab.
Chapter 1Physical Quantities and Measurements
Chapter 2Kinematics
Chapter 3Dynamics
Chapter 4Turning Effect of Forces
Chapter 5Work and Energy
Chapter 6Mechanical Properties of Matter
Chapter 7✨ Thermal Properties of Matter
Chapter 8Magnetism
Chapter 9Nature of Science
📖 Complete syllabus coverage for Class 9 Physics (PECTAA 2026) – Chapters 1 to 9
Created by Hira Science Academy | Aligned with PECTAA 2026 Syllabus