Prepare for the Punjab Board Annual Examinations 2027 with our Class 10 Physics Chapter 10: Thermal Physics – Test No. 2. This board-standard full unit model paper is specially designed according to the new Physics syllabus issued by PECTAA Punjab. Students can access a free PDF download of this Class 10 Physics test to practice important questions, assess their subject knowledge, and strengthen their exam preparation. This paper is part of our comprehensive Class 10 Physics Chapter-Wise Test Series and Punjab Board 2027 Model Papers, designed to help students prepare effectively for their matric examinations.
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Chapter Wise Class Test
T-2
Chapter-10
Thermal Physics
1.1 Choose the correct Answer.(Time: 7 Minutes)(Total Marks: 7)
1.
Which of the following liquids evaporates faster?
(a) Alcohol(b) Water(c) Oil(d) Mercury
Ans: (a) Alcohol is a volatile liquid with weak forces between its molecules, so it evaporates fastest.
2.
The latent heat of fusion of ice is:
(a) 2.26 × 106 J kg−1(b) 3.36 × 105 J kg−1(c) 1.4 × 106 J kg−1(d) 5.4 × 106 J kg−1
Ans: (b) The latent heat of fusion of ice is 3.36 × 105 J kg−1.
3.
The latent heat of vaporization is needed to:
(a) Liquid to solid(b) Liquid to gas(c) Solid to gas(d) Gas to liquid
Ans: (b) Latent heat of vaporization is the heat needed to change a liquid into gas at its boiling point.
4.
On which temperature mercury becomes super conductor?
(a) 7.2 K(b) 135 K(c) 4.2 K(d) 100 K
Ans: (c) Mercury becomes a superconductor at 4.2 K (critical temperature).
5.
In a superconductor, what happens to the electric current flow?
(a) It faces high resistance(b) It flows without any energy loss(c) It decreases over time(d) It gets blocked by obstacles
Ans: (b) A superconductor has zero resistance, so current flows without any energy loss.
6.
Which property determines how much heat a solid can absorb before its temperature changes significantly?
(a) Density(b) Specific heat capacity(c) Colour(d) Hardness
Ans: (b) Specific heat capacity (Q = mcΔT) decides how much heat is absorbed per unit temperature rise.
7.
High-temperature superconductors typically involve which type of material?
(a) Pure metals(b) Organic compounds(c) Ceramics(d) Liquid crystals
Ans: (c) High-temperature superconductors are mostly ceramic compounds (e.g. copper-oxide ceramics).
Class 10 Physics | Chapter-10: Thermal Physics | T-2 Objective Type
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Chapter Wise Class Test
T-2
Chapter-10
Thermal Physics
Total Marks: 23(Subjective Type)Time: 33 Minutes
2.Write short answers to any Seven (7) questions.[7 × 2 = 14]
(i)
Why does a wet cloth dry faster on a hot day?
On a hot day the water molecules gain more kinetic energy, so more molecules escape from the surface per second. Hence evaporation is faster and the cloth dries sooner.
(ii)
What happens to water when it evaporates from our skin?
The fastest water molecules take their energy (latent heat) from the skin and escape into the air as vapour. The skin loses heat and feels cool.
(iii)
Why does evaporation occur at room temperature?
Molecules of a liquid move with different speeds. Some surface molecules always have enough energy to overcome the attractive forces and escape, so evaporation takes place at every temperature, not only at the boiling point.
(iv)
If evaporation produces cooling, why does not boiling water feel cold?
Boiling water is continuously supplied with heat by the burner. This heat provides the latent heat of vaporization, so the temperature stays at 100°C and the water does not cool; it feels hot.
(v)
What is the relation of Latent heat of fusion to the melting of solid?
During melting, the heat absorbed at the melting point is used to break the bonds between molecules, not to raise the temperature. The heat needed to melt a solid is Q = mLf, so a larger latent heat of fusion means more heat is required to melt the same mass.
(vi)
How does superconductivity work?
When some materials are cooled below a critical temperature, their electrical resistance drops to zero. Electrons then move through the material in pairs (Cooper pairs) without colliding with atoms, so current flows without any loss of energy. Example: mercury at 4.2 K.
(vii)
What are some uses of superconductors?
- MRI machines in hospitals (strong magnets)
- Magnetic levitation (maglev) trains
- Power cables with no energy loss
- Particle accelerators and powerful electromagnets
- Very sensitive magnetic sensors and fast electronic circuits
(viii)
Why does a liquid evaporate faster when the air is dry?
Dry air contains very little water vapour, so few vapour molecules return to the liquid. More molecules escape than come back, and the net rate of evaporation increases.
(ix)
Why do electric transmission wires sag in summer and tighten in winter?
In summer the heat expands the metal wires, so they become longer and sag. In winter they contract and become tight. Therefore the wires are hung slightly loose so that they do not snap in winter.
3.Give Answers of the following questions.[4 + 5 = 9]
(i)
Why do solids, liquids, and gases expand when heated? Explain with examples.
On heating, the molecules gain kinetic energy and vibrate or move faster, so the average distance between them increases and the substance expands.
- Solids expand least: ΔL = αL0ΔT. Example: railway tracks and bridges expand in summer.
- Liquids expand more than solids: ΔV = βV0ΔT. Example: mercury rises in a thermometer; a full petrol tank overflows when warmed.
- Gases expand the most. Example: a balloon swells in the sun; hot air rises in a hot air balloon.
(ii)
Calculate the heat required to completely vaporize 1 kg of water at 100 °C. (Latent heat of vaporization of water = 2.26×106 J kg-4)
Given: m = 1 kg, Lv = 2.26 × 106 J kg−1 (the paper prints the unit as J kg−4, which should be J kg−1)
Q = mLv = 1 × 2.26 × 106 = 2.26 × 106 J (= 2260 kJ)
Q = mLv = 1 × 2.26 × 106 = 2.26 × 106 J (= 2260 kJ)
Class 10 Physics | Chapter-10: Thermal Physics | T-2 Subjective Type
