Thermal physics gives NEET several short numericals that test one formula each. This set covers calorimetry, thermal expansion, conduction and radiation, the first law, isothermal and adiabatic processes, Carnot engines and refrigerators, and the kinetic theory of gases, all from NCERT Class 11.
How to practise: read each question and tap the option you think is correct. You will see right away whether you got it, along with a short explanation, and your score is tracked at the bottom of the screen. This set has 15 questions.
Topics covered in this set
- Calorimetry and latent heat
- Thermal expansion
- Conduction and radiation laws
- First law and thermodynamic processes
- Carnot engine and refrigerator
- Kinetic theory, degrees of freedom and specific heats
NEET Physics MCQs with answers and explanations
Q1. 100 g of water at 80 °C is mixed with 200 g of water at 20 °C in an insulated container. What is the final temperature of the mixture? (Neglect heat taken by the container)
a) 50 °C
b) 60 °C
c) 30 °C
d) 40 °C
Q2. How much heat is needed to convert 10 g of ice at 0 °C into water at 20 °C? (Latent heat of fusion = 80 cal/g, specific heat of water = 1 cal/g °C)
a) 200 cal
b) 1000 cal
c) 800 cal
d) 600 cal
Q3. A steel rod 2 m long is heated through 50 °C. The coefficient of linear expansion of steel is 1.2 × 10⁻⁵ °C⁻¹. By how much does its length increase?
a) 12 mm
b) 0.6 mm
c) 1.2 mm
d) 2.4 mm
Q4. Two slabs of equal thickness and equal area, with thermal conductivities k and 2k, are joined face to face in series. What is the equivalent thermal conductivity of the combination?
a) 3k
b) 4k/3
c) 2k/3
d) 3k/2
Q5. The absolute temperature of a black body is doubled. By what factor does the power it radiates increase?
a) 4
b) 2
c) 8
d) 16
Q6. The spectrum of a star peaks at a wavelength of 500 nm. Taking Wien's constant b = 2.9 × 10⁻³ m K, what is the surface temperature of the star?
a) 1450 K
b) 5800 K
c) 11600 K
d) 2900 K
Q7. A gas absorbs 500 J of heat and does 200 J of work on its surroundings. What is the change in its internal energy?
a) −300 J
b) +700 J
c) +300 J
d) −700 J
Q8. 2 mol of an ideal gas is heated at constant pressure so that its temperature rises by 50 K. How much work does the gas do? (R = 8.31 J mol⁻¹ K⁻¹)
a) 1662 J
b) 831 J
c) 2077.5 J
d) 415.5 J
Q9. A monatomic ideal gas (γ = 5/3) is compressed adiabatically to one-eighth of its initial volume. Its absolute temperature becomes:
a) 8 times
b) 4 times
c) 2 times
d) 16 times
Q10. A diatomic ideal gas (Cv = 5R/2) is heated at constant pressure. What fraction of the heat supplied goes into increasing its internal energy?
a) 2/7
b) 2/5
c) 5/7
d) 3/5
Q11. A Carnot engine works between a source at 527 °C and a sink at 127 °C. What is its efficiency?
a) 76%
b) 40%
c) 50%
d) 25%
Q12. A Carnot refrigerator keeps its inside at 250 K while the room is at 300 K. What is its coefficient of performance?
a) 1.2
b) 5
c) 6
d) 0.2
Q13. The temperature of an ideal gas is raised from 27 °C to 927 °C. Its rms molecular speed becomes:
a) 2 times
b) √2 times
c) 4 times
d) Unchanged
Q14. What is the ratio of the rms speed of hydrogen molecules to that of oxygen molecules at the same temperature? (Molar masses: H₂ = 2 g/mol, O₂ = 32 g/mol)
a) 16 : 1
b) 1 : 4
c) 8 : 1
d) 4 : 1
Q15. One mole of a monatomic ideal gas is mixed with one mole of a rigid diatomic ideal gas. What is the ratio Cp/Cv of the mixture?
a) 1.67
b) 1.33
c) 1.5
d) 1.4
Quick revision notes
- Calorimetry: heat lost = heat gained; phase change uses Q = mL with no temperature change.
- Expansion: ΔL = LαΔT; β = 2α and γ = 3α for isotropic solids.
- Radiation: P ∝ T⁴ (Stefan); λ_m T = b (Wien). Slabs in series: thermal resistances add.
- First law ΔU = Q − W; isobaric W = nRΔT; adiabatic TV^(γ−1) = constant.
- Carnot: η = 1 − T₂/T₁, refrigerator β = T₂/(T₁ − T₂); v_rms = √(3RT/M); Cp − Cv = R.
Frequently asked questions
Are these NEET previous year questions?
No. They are original practice questions based on the NCERT Class 11 chapters Thermal Properties of Matter, Thermodynamics and Kinetic Theory.
Should temperatures be converted to kelvin?
Always use kelvin in Carnot efficiency, gas laws, rms speed and radiation laws. Temperature differences alone, as in calorimetry and expansion, are the same in °C and K.
How do I remember γ for different gases?
Use γ = 1 + 2/f, where f is the degrees of freedom: f = 3 for monatomic (γ = 5/3) and f = 5 for rigid diatomic (γ = 7/5).
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