THERMAL PROPERTIES OF MATTER-Objective Questions for Entrance Exams
Thermal Properties of Matter is one of the most concept-driven chapters in Physics, forming a crucial bridge between microscopic particle behavior and macroscopic physical observations. Questions from this unit appear consistently in competitive examinations such as JEE (Main & Advanced), NEET, AIIMS, BITSAT, KVPY, Olympiads, and various state-level engineering and medical entrance tests. The chapter demands not only clarity of definitions and formulas but also a strong physical intuition about expansion, thermal stress, and material behavior under temperature variations.
The following MCQs are carefully curated and modeled on previously asked questions and standard competitive patterns, ensuring alignment with the NCERT syllabus while matching the difficulty gradient of national-level entrance exams. Each question emphasizes analytical reasoning, dimensional understanding, and application-based learning rather than rote memorization. Detailed explanations accompany every answer to reinforce conceptual clarity, eliminate common misconceptions, and strengthen problem-solving confidence.
This MCQ set is ideal for revision, mock-test practice, and conceptual reinforcement, enabling students to transition smoothly from textbook understanding to competitive exam readiness.
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Q1
Two rods of same material but lengths \(L\) and \(2L\) are heated through the same temperature rise. The ratio of increase in length is (Exam:Year: 1998)
(A) \(1:1\)
(B) \(1:2\)
(C) \(2:1\)
(D) \(1:4\)
✅ Correct: (B)
Q2
The unit of coefficient of linear expansion is (Exam: Year: 2016)
(A) K
(B) \(K^{-1}\)
(C) m/K
(D) dimensionless
✅ Correct: (B)
Q3
A metal sphere fits exactly in a ring at \(20^\circ\)C. On heating both, the sphere will (Exam:Year: 2009)
(A) fall out
(B) not pass
(C) crack the ring
(D) remain just fitted
✅ Correct: (D)
Q4
If the temperature of a body increases by \(1^\circ\)C, its volume increases by \(1\%\). The coefficient of volume expansion is (Exam: Year: 2014)
(A) \(0.01\)
(B) \(0.1\)
(C) \(1\)
(D) \(10^{-2}\,^\circ\text{C}^{-1}\)
✅ Correct: (D)
Q5
For an isotropic solid, relation between \(\alpha\) and \(\beta\) is (Exam:Year: 2012)
(A) \(\beta=\alpha\)
(B) \(\beta=2\alpha\)
(C) \(\beta=3\alpha\)
(D) \(\beta=\alpha/3\)
✅ Correct: (C)
Q6
The apparent expansion of a liquid is due to (Exam: State Engineering Year: 2010)
(A) expansion of liquid only
(B) expansion of container only
(C) difference of real expansions
(D) contraction of container
✅ Correct: (C)
Q7
A steel rail is laid at \(10^\circ\)C. At \(50^\circ\)C\), it buckles because (Exam: IIT-JEE Year: 2001)
(A) mass increases
(B) density decreases
(C) thermal stress develops
(D) length decreases
✅ Correct: (C)
Q8
Thermal stress developed when expansion is prevented is (Exam: NEET Year: 2019)
(A) \(Y\alpha\Delta T\)
(B) \(\alpha\Delta T/Y\)
(C) \(Y/(\alpha\Delta T)\)
(D) zero
✅ Correct: (A)
Q9
The coefficient of superficial expansion of a solid is approximately (Exam: IIT-JEE Year: 1996)
(A) \(\alpha\)
(B) \(2\alpha\)
(C) \(3\alpha\)
(D) \(\alpha/2\)
✅ Correct: (B)
Q10
Which material shows maximum thermal expansion? (Exam: NEET Year: 2015)
(A) Steel
(B) Copper
(C) Aluminium
(D) Invar
✅ Correct: (C)
Q11
Invar is used in pendulum rods because (Exam: IIT-JEE Year: 1999)
(A) high density
(B) low conductivity
(C) very small \(\alpha\)
(D) high elasticity
✅ Correct: (C)
Q12
A bimetallic strip bends on heating due to (Exam: Olympiad Year: 2013)
(A) unequal masses
(B) unequal lengths
(C) different expansion coefficients
(D) unequal densities
✅ Correct: (C)
Q13
Which of the following has maximum thermal stress for same \(\Delta T\)? (Exam: BITSAT Year: 2011)
(A) Rubber
(B) Steel
(C) Glass
(D) Lead
✅ Correct: (B)
Q14
The real expansion of a liquid is measured by (Exam: AIIMS Year: 2008)
(A) ignoring container expansion
(B) subtracting container expansion
(C) adding container expansion
(D) measuring apparent expansion
✅ Correct: (B)
Q15
A hole in a metal plate when heated (Exam: IIT-JEE Year: 1985)
(A) shrinks
(B) remains same
(C) expands
(D) collapses
✅ Correct: (C)
Q16
Coefficient of linear expansion depends on (Exam: NEET Year: 2020)
(A) length only
(B) temperature range
(C) material nature
(D) shape
✅ Correct: (C)
Q17
When temperature is doubled, \(\alpha\) (Exam: State Engineering Year: 2012)
(A) doubles
(B) halves
(C) remains nearly same
(D) becomes zero
✅ Correct: (C)
Q18
Thermal strain is (Exam: IIT-JEE Year: 2000)
(A) \(\alpha\Delta T\)
(B) \(Y\alpha\Delta T\)
(C) \(\Delta T/\alpha\)
(D) zero
✅ Correct: (A)
Q19
Which does not change on heating? (Exam: NEET Year: 2013)
(A) mass
(B) length
(C) area
(D) volume
✅ Correct: (A)
Q20
If \(\alpha_1>\alpha_2\) in a bimetallic strip, it bends towards (Exam: Olympiad Year: 2011)
(A) metal 1
(B) metal 2
(C) middle
(D) randomly
✅ Correct: (B)
Q21
Unit of thermal stress is (Exam: IIT-JEE Year: 1994)
(A) J
(B) N
(C) Pa
(D) K
✅ Correct: (C)
Q22
Apparent expansion of mercury in glass is (Exam: AIIMS Year: 2007)
(A) more than real
(B) less than real
(C) equal to real
(D) zero
✅ Correct: (B)
Q23
Linear expansion is negligible for (Exam: NEET Year: 2018)
(A) solids
(B) liquids
(C) gases
(D) plasma
✅ Correct: (C)
Q24
A wire fixed at both ends is heated. It develops (Exam: IIT-JEE Year: 2003)
(A) tensile stress
(B) compressive stress
(C) shear stress
(D) no stress
✅ Correct: (B)
Q25
The coefficient of volume expansion of water at \(4^\circ\)C is (Exam: NEET Year: 2017)
(A) maximum
(B) minimum
(C) zero
(D) negative infinity
✅ Correct: (C)
Q26
If a cube expands uniformly, fractional change in volume equals (Exam: IIT-JEE Year: 1992)
(A) \(\alpha\Delta T\)
(B) \(2\alpha\Delta T\)
(C) \(3\alpha\Delta T\)
(D) \(\alpha/3\)
✅ Correct: (C)
Q27
Which is true for thermal expansion? (Exam: BITSAT Year: 2010)
(A) always linear
(B) independent of temperature
(C) depends on temperature range
(D) zero for solids
✅ Correct: (C)
Q28
Railway tracks have gaps to (Exam: NEET Year: 2014)
(A) reduce friction
(B) save material
(C) avoid buckling
(D) increase strength
✅ Correct: (C)
Q29
The apparent coefficient of expansion of liquid is (Exam: State Engineering Year: 2015)
(A) \(\beta_l\)
(B) \(\beta_l-\beta_c\)
(C) \(\beta_l+\beta_c\)
(D) \(\beta_c\)
✅ Correct: (B)
Q30
Which has least thermal expansion? (Exam: IIT-JEE Year: 1997)
(A) Aluminium
(B) Copper
(C) Steel
(D) Invar
✅ Correct: (D)
Q31
Stress produced due to temperature change depends on (Exam: NEET Year: 2021)
(A) mass
(B) shape
(C) Young’s modulus
(D) volume
✅ Correct: (C)
Q32
Heating a solid uniformly causes (Exam: Olympiad Year: 2014)
(A) only length change
(B) only volume change
(C) shape change
(D) no shape change
✅ Correct: (D)
Q33
The ratio of superficial to linear expansion coefficients is (Exam: IIT-JEE Year: 1988)
(A) 1
(B) 2
(C) 3
(D) 1/2
✅ Correct: (B)
Q34
A liquid is heated in a vessel of same material. Apparent expansion is (Exam: NEET Year: 2012)
(A) zero
(B) real
(C) negative
(D) less than real
✅ Correct: (D)
Q35
Thermal expansion is minimum in (Exam: AIIMS Year: 2010)
(A) solids
(B) liquids
(C) gases
(D) vapours
✅ Correct: (A)
Q36
Coefficient of linear expansion is independent of (Exam: IIT-JEE Year: 1991)
(A) temperature
(B) material
(C) initial length
(D) pressure
✅ Correct: (C)
Q37
On heating, density of a solid (Exam: NEET Year: 2016)
(A) increases
(B) decreases
(C) remains same
(D) becomes zero
✅ Correct: (B)
Q38
The expansion joint in bridges is provided due to (Exam: State Engineering Year: 2018)
(A) vibration
(B) corrosion
(C) thermal expansion
(D) elasticity
✅ Correct: (C)
Q39
Which expands most per degree rise? (Exam: BITSAT Year: 2013)
(A) solid
(B) liquid
(C) gas
(D) all equal
✅ Correct: (C)
Q40
A rod free to expand has no thermal stress because (Exam: IIT-JEE Year: 2005)
(A) no expansion
(B) no force developed
(C) \(\alpha=0\)
(D) \(Y=0\)
✅ Correct: (B)
Q41
Thermal expansion is an example of (Exam: NEET Year: 2011)
(A) elastic deformation
(B) plastic deformation
(C) fracture
(D) creep
✅ Correct: (A)
Q42
Which graph represents linear expansion? (Exam: Olympiad Year: 2015)
(A) \(\Delta L\) vs \(T\) straight line
(B) curved
(C) exponential
(D) random
✅ Correct: (A)
Q43
A glass tumbler cracks when hot water is poured because (Exam: AIIMS Year: 2006)
(A) uniform expansion
(B) non-uniform expansion
(C) contraction
(D) pressure increase
✅ Correct: (B)
Q44
Which is dimensionless? (Exam: IIT-JEE Year: 1989)
(A) \(\alpha\)
(B) \(\beta\)
(C) thermal strain
(D) thermal stress
✅ Correct: (C)
Q45
A cube has side \(a\). Increase in side on heating by \(\Delta T\) is (Exam: NEET Year: 2019)
(A) \(\alpha a\Delta T\)
(B) \(3\alpha a\Delta T\)
(C) \(\beta a\Delta T\)
(D) \(2\alpha a\Delta T\)
✅ Correct: (A)
Q46
The phenomenon of bending of a thermostat is due to (Exam: BITSAT Year: 2012)
(A) elasticity
(B) thermal stress
(C) bimetallic expansion
(D) conduction
✅ Correct: (C)
Q47
Real expansion of a liquid is always (Exam: NEET Year: 2010)
(A) less than apparent
(B) equal to apparent
(C) greater than apparent
(D) zero
✅ Correct: (C)
Q48
Thermal expansion coefficient is maximum for (Exam: IIT-JEE Year: 1993)
(A) diamond
(B) iron
(C) aluminium
(D) invar
✅ Correct: (C)
Q49
If temperature change is zero, thermal stress is (Exam: State Engineering Year: 2016)
(A) maximum
(B) minimum
(C) zero
(D) infinite
✅ Correct: (C)
Q50
Expansion of solids on heating is due to (Exam: Olympiad Year: 2016)
(A) increase in atomic size
(B) decrease in binding force
(C) increase in mean separation
(D) change in mass
✅ Correct: (C)
Frequently Asked Questions
Temperature is a measure of the degree of hotness or coldness of a body and determines the direction of heat flow.
Heat is a form of energy transferred from one body to another due to a temperature difference.
No
Thermal equilibrium is the state in which bodies in contact attain the same temperature and no net heat transfer occurs.
If two systems are each in thermal equilibrium with a third system
It forms the basis of temperature measurement and the construction of thermometers.
Thermal expansion is the increase in dimensions of a substance when its temperature rises.
Linear expansion
It is the fractional change in length per unit original length per unit rise in temperature.
Change in length is given by \( \Delta L = L_0 \alpha \Delta T \).
Areal expansion is the increase in surface area of a solid due to rise in temperature.
Volumetric expansion is the increase in volume of a substance with temperature.
For isotropic solids
To allow thermal expansion and prevent buckling during high temperatures.
Water contracts on heating from \(0^\circ\text{C}\) to \(4^\circ\text{C}\) and expands beyond \(4^\circ\text{C}\).
