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Chapter 7. Temperature and its Measurement

Chapter Review

Chapter 7. Temperature and its Measurement

Chapter Review

Temperature is one of the most important physical quantities that helps us understand how hot or cold an object is. Every day we experience different temperatures around us. We feel cool air in the morning, warm sunshine during the afternoon, and cold weather during winter. Although our sense of touch gives us a rough idea of temperature, it cannot always provide correct information. Science uses measuring instruments called thermometers to determine temperature accurately.

This chapter introduces students to the concept of temperature and explains why accurate measurement is necessary in daily life, science laboratories, hospitals, industries, and weather forecasting. It also explains different types of thermometers, temperature scales, correct measuring techniques, and safety precautions while using thermometers. :contentReference[oaicite:1]{index=1}

Introduction

Imagine touching a metal spoon and a wooden spoon kept in the same room. The metal spoon may feel colder even though both objects are actually at the same temperature. This simple observation shows that our sense of touch is not always reliable. Scientists therefore developed instruments that measure temperature accurately without depending on our feelings.

Temperature measurement plays an important role in healthcare, cooking, scientific experiments, weather reports, agriculture, manufacturing industries, food storage, and environmental studies. A doctor checks body temperature to diagnose fever, while scientists use laboratory thermometers during experiments. Weather stations continuously monitor air temperature to prepare weather forecasts.

The NCERT Curiosity chapter begins with a simple activity where one hand is placed in warm water and the other in cold water before both are placed in normal water. Surprisingly, each hand experiences the same water differently. This experiment clearly proves that touch cannot accurately measure temperature and that scientific instruments are essential. :contentReference[oaicite:2]{index=2}

What is Temperature?

Temperature is the scientific measure of the degree of hotness or coldness of a body. Every object contains heat energy because its particles are constantly moving. Faster-moving particles possess more energy, making the object hotter. Slower-moving particles have less energy, making the object cooler.

Temperature does not measure the total amount of heat present in an object. Instead, it indicates how hot or cold the object is when compared with another object. For example, boiling water has a much higher temperature than ice water because the particles in boiling water move much faster.

Scientists use thermometers because they provide numerical values instead of guesses. Numerical measurements help everyone obtain the same result regardless of who performs the measurement.

Why We Cannot Always Trust Our Sense of Touch

Our skin responds to changes in temperature rather than measuring the exact temperature. When our hand is first placed in warm water, it becomes adapted to warmth. Similarly, a hand placed in cold water becomes adapted to coldness. If both hands are then placed in water at room temperature, one hand feels the water cold while the other feels it warm.

This demonstrates that human sensation depends upon previous conditions rather than actual temperature. Therefore, scientific measurements are always preferred whenever accuracy is required.

Classification of Thermometers

Type	Main Use	Features
Clinical Thermometer	Measures human body temperature	Used by doctors and at home
Digital Clinical Thermometer	Measures body temperature electronically	Fast, safe and easy to read
Laboratory Thermometer	Measures temperature of liquids and laboratory materials	Wide temperature range
Room Thermometer	Measures surrounding air temperature	Used indoors
Infrared Thermometer	Measures temperature without touching the body	Useful in hospitals and airports

Clinical Thermometer

A clinical thermometer is specially designed to measure human body temperature. Modern digital thermometers use electronic sensors instead of mercury, making them safer and easier to use. They provide quick readings and reduce the risk associated with broken mercury thermometers. The thermometer should be cleaned before and after every use for proper hygiene. :contentReference[oaicite:3]{index=3}

Laboratory Thermometer

Laboratory thermometers are used during scientific experiments to measure the temperature of liquids and other substances. Unlike clinical thermometers, they can measure temperatures over a much wider range. They should always be held vertically, and the bulb should not touch the sides or bottom of the container while measuring temperature. The reading should be taken while the thermometer is still immersed in the liquid. :contentReference[oaicite:4]{index=4}

Temperature Scales

Scientists use different temperature scales depending on the purpose of measurement.

Scale	Unit	Common Use
Celsius Scale	°C	Daily life and science
Fahrenheit Scale	°F	Used in some countries
Kelvin Scale	K	SI unit used in scientific research

The normal body temperature of a healthy adult is approximately 37°C, which is equal to 98.6°F. The SI unit of temperature is kelvin (K). Scientists commonly use Kelvin in advanced scientific work because many physical laws are based on this scale. :contentReference[oaicite:5]{index=5}

Working Principle of Thermometers

Digital thermometers contain heat-sensitive electronic sensors that detect changes in temperature and display the reading on a screen. Laboratory thermometers generally use coloured alcohol or mercury that expands when heated and contracts when cooled. The rise or fall of the liquid column indicates the temperature.

Both types of thermometers convert physical changes caused by heat into readable numerical values.

Applications of Temperature Measurement

• Checking fever and monitoring health.
• Performing scientific laboratory experiments.
• Preparing daily weather forecasts.
• Monitoring food storage conditions.
• Industrial quality control.
• Agricultural planning.
• Medical research.
• Environmental monitoring.
• Cooking and food processing.
• Renewable energy research.

Important Terms

Term	Meaning
Temperature	Measure of hotness or coldness.
Thermometer	Instrument used to measure temperature.
Clinical Thermometer	Thermometer used for body temperature.
Laboratory Thermometer	Thermometer used in scientific experiments.
Celsius	Common temperature scale.
Fahrenheit	Temperature scale mainly used in a few countries.
Kelvin	SI unit of temperature.
Infrared Thermometer	Non-contact thermometer.

Chapter Highlights

• Temperature indicates how hot or cold an object is.
• Human touch cannot accurately determine temperature.
• Thermometers provide reliable temperature measurements.
• Clinical thermometers measure body temperature.
• Laboratory thermometers measure temperatures of different substances.
• The Celsius, Fahrenheit and Kelvin scales are commonly used.
• 37°C (98.6°F) is considered the average normal body temperature.
• The SI unit of temperature is kelvin (K).
• Digital thermometers are safer than traditional mercury thermometers.
• Correct handling and proper precautions improve measurement accuracy.
• Temperature measurement is essential in medicine, laboratories, industries and weather forecasting.

Chapter 7. Temperature and its Measurement

NCERT TextBook Questions With Answers

Chapter 7. Temperature and its Measurement

NCERT Textbook Exercise

Question 1. The normal temperature of a healthy human being is close to __________.

Options:

• (A) 98.6 °C
• (B) 37.0 °C
• (C) 32.0 °C
• (D) 27.0 °C

Answer: (B) 37.0 °C

Explanation: The average normal body temperature of a healthy human being is about 37°C, which is equivalent to 98.6°F. However, slight variations may occur depending on age, activity, and time of the day. :contentReference[oaicite:0]{index=0}

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Question 2. 37°C is the same temperature as __________.

Options:

• (A) 97.4°F
• (B) 97.6°F
• (C) 98.4°F
• (D) 98.6°F

Answer: (D) 98.6°F

Explanation: Celsius and Fahrenheit are two commonly used temperature scales. A body temperature of 37°C is equal to 98.6°F. :contentReference[oaicite:1]{index=1}

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Question 3. Fill in the blanks.

(i) The hotness or coldness of a system is determined by its __________________.

Answer: temperature

Explanation: Temperature tells us how hot or cold an object is compared with another object.

 

(ii) The temperature of ice-cold water cannot be measured by a __________________ thermometer.

 

Answer: clinical

Explanation: A clinical thermometer is designed only for measuring human body temperature. Ice-cold water is outside its measuring range. :contentReference[oaicite:2]{index=2}

 

(iii) The unit of temperature is degree __________________.

 

Answer: Celsius

Explanation: The commonly used unit for measuring temperature is degree Celsius (°C).

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Question 4. The range of a laboratory thermometer is usually __________.

Options:

• (A) 10°C to 100°C
• (B) –10°C to 110°C
• (C) 32°C to 45°C
• (D) 35°C to 42°C

Answer: (B) –10°C to 110°C

Explanation: Laboratory thermometers have a much wider range than clinical thermometers and are suitable for measuring the temperatures of different substances. :contentReference[oaicite:3]{index=3}

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Question 5. Four students used a laboratory thermometer to measure the temperature of water as shown in the figure. Who followed the correct method?

Options:

• (A) Student 1
• (B) Student 2
• (C) Student 3
• (D) Student 4

Answer: (C) Student 3

Explanation:

• The thermometer should be held vertically.
• The bulb should remain immersed in water.
• The bulb should not touch the sides or bottom of the container.
• The reading should be taken while the thermometer is still inside the water.

Student 3 follows all these precautions correctly. :contentReference[oaicite:4]{index=4}

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Question 6. Colour the liquid column on the thermometer diagrams to show the following temperatures:

• (i) 14°C
• (ii) 17°C
• (iii) 7.5°C

Answer:

This is a practical activity. Draw the red liquid column up to the given temperature marks on each thermometer carefully using a ruler.

Explanation: Ensure that the top of the coloured column exactly matches the required temperature marking.

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Question 7. Observe the thermometer shown in the figure and answer the following questions.

(i) What type of thermometer is it?

Answer: It is a laboratory thermometer.

 

(ii) What is the reading of the thermometer?

 

Answer: Read the temperature by observing the top of the liquid column in the given figure. (The exact value depends on the printed diagram in the textbook.)

 

(iii) What is the smallest value that this thermometer can measure?

 

Answer: 1°C

Explanation: The thermometer has ten equal divisions between two successive 10°C markings. Therefore, each small division represents 1°C. :contentReference[oaicite:5]{index=5}

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Question 8. A laboratory thermometer is not used to measure our body temperature. Give a reason.

Answer:

A laboratory thermometer is designed for measuring the temperature of liquids and other substances over a wide range. It does not have the design features required to safely and accurately measure human body temperature. Unlike a clinical thermometer, its reading changes immediately when removed from the object being measured, making it unsuitable for measuring body temperature.

Explanation:

• Clinical thermometers are specially designed for the human body.
• Laboratory thermometers are meant for experiments.
• Using the correct thermometer ensures accurate and safe temperature measurement.

Chapter 7. Temperature and its Measurement

Extra Questions Examination Based

Chapter 7. Temperature and its Measurement

Temperature is an important concept in science that helps us understand how hot or cold an object is. In this chapter, students will learn about different types of thermometers, temperature scales, and the correct methods of measuring temperature.

Important Questions with Answers

The following important questions are designed according to the latest CBSE pattern. They cover conceptual understanding, application-based learning, and examination-oriented practice.

1 Mark Questions

Question 1. What is temperature?

Answer: Temperature is the measure of the degree of hotness or coldness of a body.

Question 2. Name the instrument used to measure temperature.

Answer: A thermometer is used to measure temperature.

Question 3. What is the SI unit of temperature?

Answer: The SI unit of temperature is kelvin (K).

Question 4. What is the normal body temperature of a healthy adult in Celsius?

Answer: Approximately 37°C.

Question 5. Which thermometer is used to measure human body temperature?

Answer: A clinical thermometer.

Question 6. Name the thermometer used in science laboratories.

Answer: A laboratory thermometer.

Question 7. Why is our sense of touch not reliable for measuring temperature?

Answer: Our sense of touch depends on previous exposure to hot or cold objects and cannot measure temperature accurately.

Question 8. Which temperature scale is commonly used in daily life?

Answer: The Celsius scale (°C).

Question 9. What type of thermometer became popular during the COVID-19 pandemic?

Answer: An infrared (non-contact) thermometer.

Question 10. Why are digital thermometers preferred over mercury thermometers?

Answer: They are safer, easier to read, and do not contain toxic mercury. :contentReference[oaicite:0]{index=0}

2 Marks Questions

Question 1. Differentiate between a clinical thermometer and a laboratory thermometer.

Answer:

Clinical Thermometer	Laboratory Thermometer
Measures body temperature.	Measures temperature of substances.
Used in hospitals and homes.	Used in laboratories.
Has a limited temperature range.	Has a wider temperature range.

Question 2. Why should a thermometer be cleaned before and after use?

Answer:

• To maintain hygiene.
• To prevent the spread of germs from one person to another.

Question 3. Write any two precautions while using a laboratory thermometer.

Answer:

• Keep the thermometer vertical.
• The bulb should not touch the sides or bottom of the container.

Question 4. Name the three commonly used temperature scales.

Answer:

• Celsius Scale
• Fahrenheit Scale
• Kelvin Scale

Question 5. Why is a laboratory thermometer not suitable for measuring body temperature?

Answer:

• It is designed for experiments, not for the human body.
• Its reading changes immediately after it is removed from the object being measured.

3 Marks Questions

Question 1. Explain why touching an object is not always a correct way to judge its temperature.

Answer:

Our skin senses temperature relatively rather than absolutely. If one hand is kept in hot water and the other in cold water, the same lukewarm water feels cold to one hand and warm to the other. Therefore, our sense of touch cannot accurately determine temperature. A thermometer should always be used for reliable measurement.

Question 2. Explain the correct method of measuring body temperature using a digital clinical thermometer.

Answer:

• Wash the thermometer tip before use.
• Switch on or reset the thermometer.
• Place it under the tongue (or in the armpit when required).
• Wait for the beep.
• Read the displayed temperature.
• Clean the thermometer after use.

Question 3. Explain the correct method of using a laboratory thermometer.

Answer:

• Immerse only the bulb in the liquid.
• Hold the thermometer vertically.
• Do not let the bulb touch the container.
• Read the temperature while the thermometer is still inside the liquid.
• Keep your eye level with the liquid column.

Question 4. Explain the importance of measuring temperature accurately.

Answer:

Accurate temperature measurement is essential for diagnosing illnesses, conducting scientific experiments, preparing weather forecasts, maintaining food safety, industrial production, and many daily-life activities. Incorrect measurements may lead to wrong decisions and unsafe situations.

Question 5. Compare Celsius, Fahrenheit and Kelvin scales.

Answer:

Scale	Symbol	Main Use
Celsius	°C	Daily use and science
Fahrenheit	°F	Used in some countries
Kelvin	K	Scientific and SI unit

Long Answer Questions

Question 1. Explain the different types of thermometers and their uses.

Answer:

Different thermometers are designed for different purposes.

• Clinical Thermometer: Used for measuring human body temperature.
• Digital Clinical Thermometer: Gives quick and safe electronic readings.
• Laboratory Thermometer: Measures temperatures of liquids and other materials during experiments.
• Room Thermometer: Measures surrounding air temperature.
• Infrared Thermometer: Measures temperature without touching the body.

Each thermometer is specially designed for its particular purpose, so the correct thermometer should always be used.

Question 2. Describe the precautions to be followed while using a laboratory thermometer.

Answer:

• Handle it carefully because it is made of glass.
• Do not hold it by the bulb.
• Keep it vertical.
• The bulb should not touch the container.
• Read the temperature while it is immersed.
• Take the reading at eye level to avoid parallax error.

Question 3. Explain why digital thermometers have replaced mercury thermometers.

Answer:

Earlier, mercury thermometers were commonly used to measure body temperature. However, mercury is highly poisonous and may cause health and environmental hazards if the thermometer breaks. Digital thermometers use electronic heat sensors instead of mercury. They provide faster readings, are easier to read, safer for children, more hygienic, and require less maintenance. These advantages have made digital thermometers the preferred choice in homes and hospitals. :contentReference[oaicite:1]{index=1}

Question 4. Explain the importance of temperature measurement in daily life.

Answer:

Temperature measurement plays a vital role in our everyday life. Doctors use thermometers to detect fever and monitor patients. Scientists depend on accurate temperature readings during experiments. Weather departments measure air temperature to prepare forecasts. Industries monitor temperature during manufacturing processes. Refrigerators preserve food at suitable temperatures, while farmers and environmental scientists study temperature changes to improve agriculture and understand climate. Thus, accurate temperature measurement supports health, science, safety, and modern technology.

Question 5. Describe the three temperature scales used in science.

Answer:

The three commonly used temperature scales are Celsius, Fahrenheit, and Kelvin.

• Celsius Scale (°C): Most commonly used in schools, homes, and laboratories.
• Fahrenheit Scale (°F): Used mainly in a few countries for weather and body temperature.
• Kelvin Scale (K): The SI unit of temperature used in scientific research. Unlike Celsius and Fahrenheit, the Kelvin scale does not use the degree symbol.

Each scale measures the same physical quantity but uses different reference points and units.

Chapter 7. Temperature and its Measurement

40 Important MCQs with Answers

Chapter 7. Temperature and its Measurement

This MCQ practice set is prepared according to the latest CBSE pattern and is based on the NCERT Curiosity textbook. These questions help students strengthen conceptual understanding, improve analytical thinking, and prepare effectively for school examinations and competency-based assessments.

40 Important MCQs with Answer Key

Choose the most appropriate answer for each question. Read every question carefully before selecting the correct option.

1. Temperature is the measure of the ________ of a body.

(A) weight
(B) size
(C) hotness or coldness
(D) colour

2. Which instrument is used to measure temperature?

(A) Barometer
(B) Thermometer
(C) Hygrometer
(D) Ammeter

3. Which thermometer is used to measure human body temperature?

(A) Laboratory thermometer
(B) Clinical thermometer
(C) Room thermometer
(D) Weather thermometer

4. The normal body temperature of a healthy adult is about

(A) 35°C
(B) 36°C
(C) 37°C
(D) 40°C

5. 37°C is equal to

(A) 96.8°F
(B) 97.2°F
(C) 98.6°F
(D) 100°F

6. Which temperature scale is commonly used in India?

(A) Kelvin
(B) Celsius
(C) Fahrenheit
(D) Rankine

7. The SI unit of temperature is

(A) Celsius
(B) Fahrenheit
(C) Kelvin
(D) Degree

8. The symbol of kelvin is

(A) °K
(B) K
(C) k
(D) °k

9. Which thermometer became widely used during the COVID-19 pandemic?

(A) Mercury thermometer
(B) Infrared thermometer
(C) Alcohol thermometer
(D) Laboratory thermometer

10. Digital thermometers measure temperature using

(A) magnets
(B) heat sensors
(C) mirrors
(D) springs

11. Our sense of touch cannot always judge temperature correctly because

(A) skin has no nerves
(B) it depends on previous exposure to hot or cold objects
(C) objects always change temperature
(D) air changes colour

12. Which of the following is safer than a mercury thermometer?

(A) Alcohol thermometer
(B) Digital thermometer
(C) Glass rod
(D) Compass

13. Mercury thermometers are being replaced because mercury is

(A) expensive
(B) colourful
(C) poisonous
(D) heavy

14. A laboratory thermometer is mainly used for

(A) measuring body temperature
(B) measuring temperature during experiments
(C) measuring rainfall
(D) measuring pressure

15. The usual range of a laboratory thermometer is

(A) 35°C–42°C
(B) –10°C to 110°C
(C) 0°C–50°C
(D) 20°C–60°C

16. While measuring temperature with a laboratory thermometer, the bulb should

(A) touch the bottom of the container
(B) touch the side of the container
(C) remain immersed without touching the container
(D) remain outside the liquid

17. A laboratory thermometer should be held

(A) horizontally
(B) vertically
(C) upside down
(D) tilted

18. The temperature should be read

(A) after removing the thermometer from the liquid
(B) while the thermometer is immersed
(C) after shaking it
(D) after drying it

19. Eye level should be in line with the liquid column to avoid

(A) friction
(B) evaporation
(C) incorrect reading
(D) melting

20. Which liquid is commonly used in many laboratory thermometers?

(A) Petrol
(B) Alcohol
(C) Milk
(D) Oil

21. The average normal human body temperature is based on

(A) one person
(B) many healthy people
(C) children only
(D) doctors only

22. Human body temperature normally does not fall below

(A) 20°C
(B) 25°C
(C) 35°C
(D) 37°C

23. Human body temperature normally does not rise above

(A) 39°C
(B) 40°C
(C) 41°C
(D) 42°C

24. Temperature measured in the armpit is usually

(A) higher than body temperature
(B) equal to boiling point
(C) slightly lower than body temperature
(D) always 37°C

25. Fahrenheit temperature is written as

(A) K
(B) °F
(C) °C
(D) F

26. Celsius temperature is written as

(A) C
(B) °C
(C) K
(D) °K

27. Which temperature scale does not use the degree symbol?

(A) Celsius
(B) Fahrenheit
(C) Kelvin
(D) None

28. Weather reports usually mention

(A) body temperature
(B) boiling point
(C) maximum and minimum air temperature
(D) water temperature only

29. Room temperature is measured using a

(A) room thermometer
(B) clinical thermometer
(C) weighing balance
(D) rain gauge

30. Which scientist is popularly known as the 'Weather Woman of India'?

(A) Kalpana Chawla
(B) Anna Mani
(C) Janaki Ammal
(D) Asima Chatterjee

31. Air temperature is important for

(A) weather forecasting
(B) measuring mass
(C) measuring length
(D) measuring speed

32. The boiling point of water remains constant while

(A) boiling continues
(B) cooling starts
(C) freezing occurs
(D) stirring stops

33. The temperature of melting ice remains

(A) continuously increasing
(B) continuously decreasing
(C) constant while melting
(D) equal to body temperature

34. Which thermometer should never be held by its bulb?

(A) Clinical thermometer
(B) Laboratory thermometer
(C) Infrared thermometer
(D) Digital watch

35. Before using a digital thermometer, its tip should be

(A) painted
(B) heated
(C) washed and cleaned
(D) covered with paper

36. The main purpose of cleaning a thermometer is to

(A) improve colour
(B) prevent spread of germs
(C) increase temperature
(D) reduce weight

37. Temperature is compared using

(A) standard scales
(B) colours
(C) sound
(D) smell

38. Which of the following is NOT a temperature scale?

(A) Celsius
(B) Kelvin
(C) Fahrenheit
(D) Pascal

39. Which activity proves that our sense of touch is unreliable?

(A) Measuring rainfall
(B) Keeping one hand in warm water and the other in cold water before placing both in normal water
(C) Measuring length
(D) Measuring weight

40. The best conclusion from this chapter is that

(A) touch is always accurate
(B) thermometers provide reliable temperature measurements
(C) only doctors use thermometers
(D) Celsius is the only temperature scale

Answer Key

1-C, 2-B, 3-B, 4-C, 5-C, 6-B, 7-C, 8-B, 9-B, 10-B,
11-B, 12-B, 13-C, 14-B, 15-B, 16-C, 17-B, 18-B, 19-C, 20-B,
21-B, 22-C, 23-D, 24-C, 25-B, 26-B, 27-C, 28-C, 29-A, 30-B,
31-A, 32-A, 33-C, 34-B, 35-C, 36-B, 37-A, 38-D, 39-B, 40-B.