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CodeVID-P11-10-CH-01
Thermal Properties of Matter — Full Chapter Test
Name: ____________________
Roll No.: __________
Date: ____________
General Instructions
- This is a full-length test covering the whole chapter — every topic is included.
- All questions are compulsory.
- Section A carries 1 mark each, Section B 2 marks, Section C 3 marks and Section D 5 marks. Show all working for Sections B, C and D.
Section A — Multiple Choice Questions
6 × 1 = 6 marks
1.
For an isotropic solid, $\gamma$ equals:
- A.$\alpha$
- B.$2\alpha$
- C.$3\alpha$
- D.$\frac{\alpha}{2}$
2.
Water has maximum density at:
- A.$0\,^\circ$C
- B.$4\,^\circ$C
- C.$10\,^\circ$C
- D.$100\,^\circ$C
3.
The heat needed for a change of state is:
- A.$mc\,\Delta T$
- B.$mL$
- C.$\frac{m}{L}$
- D.$c\,\Delta T$
4.
The rate of conduction of heat is:
- A.$\frac{kL\,\Delta T}{A}$
- B.$\frac{kA\,\Delta T}{L}$
- C.$kAL\,\Delta T$
- D.$\frac{kA}{L\,\Delta T}$
5.
A black body radiates energy per unit area proportional to:
- A.$T$
- B.$T^2$
- C.$T^3$
- D.$T^4$
6.
Heat transfer requiring no medium is:
- A.conduction
- B.convection
- C.radiation
- D.calorimetry
Section B — Short Answer (2 marks)
4 × 2 = 8 marks
7.
Convert $98.6\,^\circ$F to the Celsius scale.
8.
State the principle of calorimetry.
9.
Why does the temperature stay constant during boiling?
10.
State Newton's law of cooling.
Section C — Short Answer (3 marks)
2 × 3 = 6 marks
11.
How much heat is needed to convert 200 g of ice at $0\,^\circ$C into water at $40\,^\circ$C? ($L_f=3.34\times10^5$, $c_w=4186$)
12.
A rod of length 1 m, area $10^{-4}\ \text{m}^2$ and $k=400\ \text{W}\,\text{m}^{-1}\,\text{K}^{-1}$ has ends at $100\,^\circ$C and $0\,^\circ$C. Find the rate of heat flow.
Section D — Long Answer (5 marks)
2 × 5 = 10 marks
13.
Explain thermal expansion in solids. Define the coefficients of linear, area and volume expansion and establish the relations $\beta=2\alpha$ and $\gamma=3\alpha$ for an isotropic solid.
14.
Describe the three modes of heat transfer and state the law of conduction and the Stefan–Boltzmann law of radiation, with one example of each mode.
Answer Key
Section A — Multiple Choice Questions
- (C) $3\alpha$
- (B) $4\,^\circ$C
- (B) $mL$
- (B) $\frac{kA\,\Delta T}{L}$
- (D) $T^4$
- (C) radiation
Section B — Short Answer (2 marks)
- $C=\frac{5}{9}(98.6-32)=\frac{5}{9}\times66.6=37\,^\circ$C.
- In an insulated system, heat lost by the hotter body equals heat gained by the colder body.
- The supplied heat becomes latent heat of vaporisation, used to break molecular bonds rather than raise temperature.
- The rate of cooling of a body is proportional to its temperature excess over the surroundings, for a small difference.
Section C — Short Answer (3 marks)
- $Q=0.2\times3.34\times10^5+0.2\times4186\times40=6.68\times10^4+3.35\times10^4=1.00\times10^5\ \text{J}$.
- $\frac{Q}{t}=\frac{400\times10^{-4}\times100}{1}=4\ \text{W}$.
Section D — Long Answer (5 marks)
- On heating, increased molecular vibration enlarges average spacing, so dimensions grow: $\Delta L=\alpha L\,\Delta T$, $\Delta A=\beta A\,\Delta T$, $\Delta V=\gamma V\,\Delta T$. For a square, $A=L^2\Rightarrow A(1+\beta\Delta T)=L^2(1+\alpha\Delta T)^2\approx L^2(1+2\alpha\Delta T)$, so $\beta=2\alpha$. For a cube, $V=L^3\Rightarrow(1+\gamma\Delta T)=(1+\alpha\Delta T)^3\approx1+3\alpha\Delta T$, so $\gamma=3\alpha$; hence $\alpha:\beta:\gamma=1:2:3$.
- Conduction: heat passes through a solid without bulk motion (a heated metal spoon), with $\frac{Q}{t}=\frac{kA\,\Delta T}{L}$. Convection: heated fluid moves and circulates (sea breezes, boiling water). Radiation: heat travels as EM waves through vacuum (the Sun's heat reaching Earth), with a black body radiating $E=\sigma T^4$, where $\sigma=5.67\times10^{-8}\ \text{W}\,\text{m}^{-2}\,\text{K}^{-4}$.
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