15 extra multiple-choice questions for Thermal Physics (10th Standard Science, Samacheer Kalvi), beyond the ones printed in the textbook — each with the correct option highlighted and a clear, worked explanation. Free to read in English and Tamil.
Q1
Each unit of the thermodynamic scale of temperature is defined as what fraction of the thermodynamic temperature of the triple point of water?
- A. 1/273.16Correct
- B. 1/273
- C. 1/373.15
- D. 1/100
Explanation. Each unit of the thermodynamic scale of temperature is defined as the fraction of 1/273.16th part of the thermodynamic temperature of the triple point of water.
Q2
Which of the following properties of a system determines the direction of the flow of heat energy when placed in contact with another system?
- A. Mass
- B. Density
- C. Volume
- D. TemperatureCorrect
Explanation. Temperature is the thermal property that determines the direction of flow of heat energy from a body at higher temperature to one at lower temperature.
Q3
What is the correct mathematical relation between the Fahrenheit scale (F) and the Kelvin scale (K) of temperature?
- A. [K] = (F + 460) \\(\times\) \\(\frac{5}{9}\)Correct
- B. [K] = (F - 460) \\(\times\) \\(\frac{5}{9}\)
- C. [K] = (F + 32) \\(\times\) \\(\frac{9}{5}\)
- D. [K] = (F - 32) \\(\times\) \\(\frac{5}{9}\)
Explanation. The relation between Fahrenheit and Kelvin scale of temperature is given by [K] = (F + 460) \\(\times\) \\(\frac{5}{9}\).
Q4
What is the value of absolute zero on the Celsius scale of temperature?
- A. -273°CCorrect
- B. 0°C
- C. -373°C
- D. 100°C
Explanation. Zero Kelvin, which represents absolute zero, is equivalent to -273°C on the Celsius temperature scale.
Q5
When a metallic system is heated and undergoes thermal expansion, what happens to its mass?
- A. It increases
- B. It decreases
- C. It remains completely unchangedCorrect
- D. It first increases then decreases
Explanation. Heating or cooling a system changes its temperature and dimensions, but the total mass of the system is not altered.
Q6
What is the SI unit of the coefficient of linear expansion of a solid substance?
- A. K
- B. \(K^{-1}\)Correct
- C. m
- D. \(m K^{-1}\)
Explanation. The coefficient of linear expansion is defined as the ratio of increase in length per unit length per degree rise in temperature, and its SI unit is \(K^{-1}\).
Q7
If a liquid is heated in a container, which of the following statements correctly describes the relationship between its real expansion and its apparent expansion?
- A. Real expansion is always less than apparent expansion
- B. Real expansion is always equal to apparent expansion
- C. Real expansion is always more than apparent expansionCorrect
- D. Real expansion can be more or less than apparent expansion depending on the container
Explanation. Due to the simultaneous expansion of the container holding the liquid, the observed apparent expansion is always less than the actual real expansion.
Q8
In an experiment to measure the real and apparent expansion of a liquid, the initial level is L1, the level after initial heating of the container is L2, and the final level is L3. How is the real expansion calculated?
- A. L3 - L1
- B. L3 - L2Correct
- C. L2 - L1
- D. L1 + L2 - L3
Explanation. The initial drop to L2 is due to container expansion, and the subsequent rise to L3 is from liquid expansion. The real expansion of the liquid is the difference L3 - L2.
Q9
According to Boyle's law, when the temperature of a fixed mass of gas is kept constant, how does the volume (V) vary with the pressure (P)?
- A. Volume is directly proportional to pressure
- B. Volume is inversely proportional to pressureCorrect
- C. Volume is proportional to the square of pressure
- D. Volume is independent of pressure
Explanation. Boyle's law states that at a constant temperature, the volume of a fixed mass of gas is inversely proportional to its pressure (P \\propto 1/V).
Q10
State which thermodynamic variable is kept constant in Charles's law, which states that volume is directly proportional to temperature.
- A. Volume
- B. Temperature
- C. Mass only
- D. PressureCorrect
Explanation. Charles's law, also known as the law of volume, states that the volume of a gas is directly proportional to its absolute temperature when the pressure is kept constant.
Q11
The ideal gas equation, PV = RT, is also referred to as the equation of state. Why is it given this name?
- A. It defines the physical state of matter of the gas
- B. It relates the state variables of the gasCorrect
- C. It describes the state of the surroundings
- D. It is only valid for gases in a solid state
Explanation. The ideal gas equation is called the equation of state because it relates the fundamental state variables (pressure, volume, and temperature) that describe the state of a gas.
Q12
One calorie is defined as the amount of heat energy required to raise the temperature of one gram of water through which of the following intervals?
- A. 1°CCorrect
- B. 1 K
- C. 1°F
- D. 10°C
Explanation. One calorie is specifically defined as the amount of heat energy required to raise the temperature of 1 gram of water by 1°C.
Q13
What is the value of the Boltzmann constant as given in the textbook evaluation section?
- A. 1.381 \\(\times 10^{-23} J K^{-1}\)Correct
- B. 8.31 J mo\(l^{-1} K^{-1}\)
- C. 6.023 \\(\times 10^{23}\) mo\(l^{-1}\)
- D. 1.381 \\(\times 10^{-23} J K\)
Explanation. The Boltzmann constant has a value of 1.381 \\(\times 10^{-23} J K^{-1}\), which relates the average kinetic energy of gas particles with their temperature.
Q14
Under what condition are the atoms or molecules of a gas considered to behave as an ideal gas?
- A. When they undergo chemical reactions
- B. When they do not interact with each otherCorrect
- C. When they exhibit high interatomic forces of attraction
- D. When they undergo zero thermal expansion
Explanation. A gas is defined as an ideal or perfect gas if its individual atoms or molecules do not interact or exert forces on one another.
Q15
What is the correct numerical value and unit of the universal gas constant (R) as described in the ideal gas equation?
- A. 8.31 J mo\(l^{-1} K^{-1}\)Correct
- B. 1.38 \\(\times 10^{-23} J K^{-1}\)
- C. 8.31 J mol K
- D. 3.81 J mo\(l^{-1} K^{-1}\)
Explanation. The universal gas constant R has a value of 8.31 J mo\(l^{-1} K^{-1}\) in the SI system, representing the molar gas constant.
Frequently asked questions
How many MCQs are there in Thermal Physics?
This chapter has 15 book-back multiple-choice questions, each with the correct answer and a step-by-step explanation.
Are these 10th Standard Science MCQs free to practise online?
Yes. Every question, answer and explanation here is free, and you can also take them as a timed practice test.
Where can I find the Thermal Physics book-back answers?
The correct option for each question is highlighted on this page with a worked explanation, plus a quick answer-key summary at the top.
