NEET UG · Physics · Thermal Properties of Matter

Heat Transfer and Thermal Expansion: NEET previous year questions

8 questions in ten years of NEET, in 6 of 10 papers. Pattern: Every year. Here is how it is asked and which ideas come back.

Asked in 10 years: 8; about 0.8 per paper
Years asked: 6/10; last asked 2026
Chance of a question next paper: 64%; historical rate, how we compute it
Weighted estimate: 0.7; model; history: 0.8 a paper on average, typically 0–2

Key findings

01
Asked in 6 of 10 papers, 8 questions in all: #103 of 204 topics by ten-year total. It comes back every 1.8 years on average.
02
67% of its questions since 2018 tested an idea never asked before; none repeated an idea from the year before.
03
The most repeated idea is Conduction through Composite Rods, asked 2 times (2017, 2025), usually as “effective conductivity of composite rod”.
04
NEET has asked 0 of the 6 ideas in this topic; 0 have never been asked, directly or indirectly.
05
Mostly asked as numerical (75%); 63% easy, 0% hard.

Questions per year

Up to 2023: 0.7; per paper
Since 2024: 1.0; 0.3
Usual gap: 1.8 yrs; between papers asking it
Swing: ±0.8; questions, year to year

How it is asked

Difficulty, format and skill

Across all 8 questions on Heat Transfer and Thermal Expansion since 2017.

Difficulty

QUESTIONS

Easy5 · 63%
Medium3 · 38%
Hard0 · 0%

Format

Numerical · 6 Q75%
One-line MCQ · 1 Q13%
Figure-based · 1 Q13%

Skill tested

Calculation · 4 Q50%
Multi-step · 2 Q25%
Recall · 1 Q13%
Application · 1 Q13%

Repeats

New idea, or one asked before?

Each column is a paper. Blue questions tested an idea NEET had not asked before; navy ones went back to an idea from an earlier paper. 2017 is the first paper, so everything in it counts as new.

’17’18’19’20’21’22’23’24’25’26

Idea asked for the first time
Idea asked in an earlier paper

Coverage of the topic

NEET has asked 0 of the 6 ideas in this topic. 0 have never been asked yet.

Asked directly0 · 0%
Touched inside another question6 · 100%
Never asked0 · 0%

Ideas come from Lumi’s syllabus map of NCERT. A never-asked idea is not a safe skip: most new questions come from exactly these.

Drill down

Idea, year, question

Every idea NEET tested in this topic, with its ten papers. Open one to read the questions.

ideaAskedShareYears’17’18’19’20’21’22’23’24’25’26

Repeated2 · 25%25%2/10
- 2025 · Q19
  Three identical heat conducting rods are connected in series as shown in the figure. The rods on the sides have thermal conductivity $2K$ …
  mediumNumerical
- 2017 · Q11
  Two rods A and B of different materials are welded together as shown in figure. Their thermal conductivities are $K_1$ and $K_2$ . The…
  mediumFigure-basedNew idea
Repeated2 · 25%25%2/10
1 · 13%13%1/10
1 · 13%13%1/10
1 · 13%13%1/10
1 · 13%13%1/10

Squares are the ten papers, 2017 to 2026; darker means more questions. Share is of the level above.

Ideas

Every idea inside this topic

6 different ideas were tested; 2 came more than once.

Conduction through Composite Rods2×
effective conductivity of composite rod
Figure-based · 6% next
Linear Thermal Expansion2×
numerical
Numerical · 6% next
Area and Volume Expansion1×
numerical
Numerical · 6% next
Thermal Conductivity1×
unit of physical quantity
One-line MCQ · 4% next
Wien's Displacement Law1×
numerical
Numerical · 4% next
Stefan-Boltzmann Law1×
numerical
Numerical · 4% next

Idea	Times	Format	Chance next	Foundation for
Conduction through Composite Rodseffective conductivity of composite rod	2	Figure-basedApplication	6%	–
Linear Thermal Expansionnumerical	2	NumericalCalculation	6%	–
Area and Volume Expansionnumerical	1	NumericalCalculation	6%	–
Thermal Conductivityunit of physical quantity	1	One-line MCQRecall	4%	–
Wien's Displacement Lawnumerical	1	NumericalMulti-step	4%	–
Stefan-Boltzmann Lawnumerical	1	NumericalCalculation	4%	–

Chance next is the historical rate at which an idea with this record came back in the following paper. It is low for every idea, which is why learning the topic beats memorising past questions. All repeated ideas

Every question

Heat Transfer and Thermal Expansion questions, year by year

The opening words of each question as it appeared in the official paper, with the idea it tested.

NEET 20261 question

Q24
The temperature of a metallic sphere of radius R is increased by a small amount $\Delta T$ . If the linear coefficient of thermal expansion…
Idea: Area and Volume Expansion
New ideaEasyNumerical

NEET 20251 question

Q19
Three identical heat conducting rods are connected in series as shown in the figure. The rods on the sides have thermal conductivity $2K$ …
Idea: Conduction through Composite Rods
MediumNumerical · figure

NEET 20241 question

Q42
A metallic bar of Young's modulus, $0.5\times10^{11}$ N m $^{-2}$ and coefficient of linear thermal expansion $10^{-5}$ °C $^{-1}$ , length 1…
Idea: Linear Thermal Expansion
EasyNumerical

NEET 20192 questions

Q14
A copper rod of 88 cm and an aluminium rod of unknown length have their increase in length independent of increase in temperature. The…
Idea: Linear Thermal Expansion
New ideaEasyNumerical
Q20
The unit of thermal conductivity is :
Idea: Thermal Conductivity
New ideaEasyOne-line MCQ

NEET 20181 question

Q43
The power radiated by a black body is P and it radiates maximum energy at wavelength, $\lambda_0$ . If the temperature of the black body is…
Idea: Wien's Displacement Law
New ideaMediumNumerical

NEET 20172 questions

Q11
Two rods A and B of different materials are welded together as shown in figure. Their thermal conductivities are $K_1$ and $K_2$ . The…
Idea: Conduction through Composite Rods
MediumFigure-based · figure
Q35
A spherical black body with a radius of 12 cm radiates 450 watt power at 500 K. If the radius were halved and the temperature doubled, the…
Idea: Stefan-Boltzmann Law
EasyNumerical

Questions from the official NEET UG papers published by NTA (CBSE before 2019). Topic and idea tags, counts and notes are Lumi’s.