Solutions to NCERT Class 6 Science Curiosity Chapter 7 Temperature and its Measurement

Students – welcome to Chapter 7 solutions. We have answered all textbook exercise questions in a clear and concise manner for your benefit. This complete solutions package has been combined with solutions to self-designed extra questions to give you additional practice. The figures are designed to help you visualise the concepts so that you can quickly and easily grasp the material. Study this material in detail and you will be well-prepared for your exams.

Solutions to ‘Let us enhance our learning’ (Page No 137) of NCERT Class 6 Science Curiosity Chapter 7 Temperature and its Measurement

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

(i) 98.6 °C
(ii) 37.0 °C
(iii) 32.0 °C
(iv) 27.0 °C

Solution: (ii) 37.0 °C

The normal temperature of a healthy human being is close to 37.0 °C.

2. 37 °C is the same temperature as _________.

(i) 97.4 °F
(ii) 97.6 °F
(iii) 98.4 °F
(iv) 98.6 °F

Solution: (iv) 98.6 °F

37 °C is the same temperature as 98.6 °F.

3. Fill in the blanks:

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

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

(iii) The unit of temperature is degree _________.

Solution:

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

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

(iii) The unit of temperature is degree Celsius.

4. The range of a laboratory thermometer is usually _________.

(i) 10 °C to 100 °C
(ii) –10 °C to 110 °C
(iii) 32 °C to 45 °C
(iv) 35 °C to 42 °C

Solution: (ii) –10 °C to 110 °C

The range of a laboratory thermometer is usually –10 °C to 110 °C.

5. Four students used a laboratory thermometer to measure the temperature of water as shown in Fig. 7.6:

Who do you think followed the correct way for measuring temperature?

(i) Student 1
(ii) Student 2
(iii) Student 3
(iv) Student 4

Solution: (ii) Student 2

Explanation: Student 2 is holding the thermometer vertically downwards and has taken care to prevent the bulb from touching the bottom or the sides of the beaker.

6. Colour to show the red column on the drawings of thermometers (Fig. 7.7) as per the temperatures written below:

Solution:

7. Observe the part of thermometer shown in Fig. 7.8 and answer the following questions:

(i) What type of thermometer is it?
(ii) What is the reading of the thermometer?
(iii) What is the smallest value that this thermometer can measure?

Solution:

(i) The thermometer is a laboratory thermometer because we can see that the scale starts from – 10 ^oC. A clinical thermometer only has the range of 35 ^oC – 42 ^oC.

(ii) The reading of the thermometer is obtained by the level of the red liquid mark which lies between 20 ^oC and 30 ^oC. The number of divisions between these marks are 10 divisions. So, one small division can read 10/10 = 1 °C. By counting, the reading = 20 ^oC + 6 ^oC = 26 ^oC.

(iii) The smallest temperature the thermometer can measure is – 10 ^oC. And as we calculated before, the smallest value that this thermometer can read is 1 °C.

8. A laboratory thermometer is not used to measure our body temperature. Give a reason.
Solution:
A laboratory thermometer is not used to measure our body temperature because it is difficult to handle. It must be held vertically upwards which is difficult to do if you are measuring temperature using the mouth or the armpits.

9. Vaishnavi has not gone to school as she is ill. Her mother has kept a record of her body temperature for three days as shown in Table 7.4.

Table 7.4: Body temperature record of Vaishnavi

(i) What was Vaishnavi’s highest recorded temperature?

(ii) On which day and at what time was Vaishnavi’s highest temperature recorded?

(iii) On which day did Vaishnavi’s temperature return to normal?

Solution:

(i) Vaishnavi’s highest recorded temperature was 40.0 ^oC.

(ii) Vaishnavi’s highest temperature was recorded on Day One at 7 pm.

(iii) Vaishnavi’s temperature returned to normal Day Three.

10. If you have to measure the temperature 22.5 °C, which of the following three thermometers will you use (Fig. 7.9)? Explain.

Solution:

Thermometer (b) can accurately measure the temperature 22.5 °C. The reason is that the temperature difference indicated between any two numbers marked on the thermometer is 10 °C and there are 20 divisions in all between them. Therefore, one small division can read 10/20 = 0.5 °C. That is, the smallest value that this thermometer can read is 0.5 °C.

In contrast the smallest temperature Thermometer (a) can measure is 1 °C and the smallest temperature Thermometer (c) can measure is 2 °C. Hence, they are not suitable for measuring 22.5 °C.

11. The temperature shown by the thermometer in Fig. 7.10 is

(i) 28.0 °C
(ii) 27.5 °C
(iii) 26.5 °C
(iv) 25.3 °C

Solution:

(ii) 27.5 °C

We determine the temperature according to the level of the mercury column. By counting the number of divisions, we get the temperature shown by the thermometer = 27 °C + 0.5 °C = 27.5 °C.

12. A laboratory thermometer has 50 divisions between 0 °C and 100 °C. What does each division of this thermometer measure?

Solution:

The total temperature difference = 100 °C– 0 °C= 100 °C.

There are 50 divisions.

Therefore, each division of the thermometer measures = 100/50 = 2 °C.

13. Draw the scale of a thermometer in which the smallest division reads 0.5 °C. You may draw only the portion between 10 °C and 20 °C.

Solution:

The required scale in Celsius is shown below:

14. Someone tells you that she has a fever of 101 degrees. Does she mean it on the Celsius scale or Fahrenheit scale?

Solution:

Our normal body temperature is 37.0 °C or 98.6 °F. Therefore, it is easy to see that 101 °C is too high of a temperature, in fact it is more than the boiling point of water. Therefore, we conclude that the person has a fever of 101 degrees on the Fahrenheit scale.

Solutions to In Text Questions of NCERT Class 6 Science Curiosity Chapter 7 Temperature and its Measurement

1. (Page 123) Can it always be correctly judged, that a person has fever, only by touching the person?
Solution:
No, it cannot always be correctly judged that a person has fever only by touching the person. The temperature of our hand may be too hot or too cold and this would give us an inaccurate reading.

2. (Page 125) Then how do we find out how hot or cold a body is?
Solution:
We can find out how hot or cold a body is by using a temperature measuring device called a thermometer.

3. (Page 128) Do small children generally have slightly higher body temperatures as compared to adults?
Solution:
Yes, small children generally have slightly higher body temperatures as compared to adults. This is because their bodies are growing and working faster.

4. (Page 128) Do old people, even when healthy, generally have lower body temperatures than young adults?
Solution:
Yes, old people, even when healthy, generally have lower body temperatures than young adults. This is because their bodies slow down as they age.

5. (Page 128) I have seen a friend of mine using a digital thermometer that reads temperature on a different scale. It shows the normal temperature of a healthy human body as 98.6 °F. What is the reason for this difference?
Solution:
The difference is because your friend’s digital thermometer measures temperature in Fahrenheit (°F), while you might be more familiar with the Celsius (°C) scale. The normal body temperatures of 98.6 °F and 37 °C are equivalent.

6. (Page 129) How can we measure temperatures beyond the range of a clinical thermometer?
Solution:
We can measure temperatures beyond the range of a clinical thermometer using a laboratory thermometer which has a much larger range.

7. (Page 132) Can we use a laboratory thermometer for measuring body temperature of a person?
Solution:
No, we cannot use a laboratory thermometer for measuring body temperature of a person because the thermometer would have to be held vertically upwards, which is inconvenient and impractical.

Extra Questions to Complement Solutions to NCERT Class 6 Science Curiosity Chapter 7 Temperature and its Measurement

Very Short Answer Type Questions:

1. Name two hot objects.
Answer:
Two hot objects are: the flame of a candle, hot tea.

2. Name two cold objects.
Answer:
Two cold objects are: ice, chilled soft drink.

3. How do we accurately measure the hotness of an object.
Answer:
We can accurately measure the hotness of an object by taking its temperature using a thermometer.

4. Name a substitute for the mercury thermometer.
Answer:
The digital thermometer is a substitute for the mercury thermometer.

5. Where is most of the mercury present in a clinical thermometer before use?
Answer:
Most of the mercury present in a bulb in the thermometer before use.

6. Name a liquid metal.
Answer:
Mercury is a liquid metal.

7. Which scale in a clinical thermometer is used in India?
Answer:
India has adopted the Celsius scale.

8. What are the two kinds of thermometers?
Answer:
There are two kinds of thermometers that you are likely to come across—clinical thermometers and laboratory thermometers.

9. What kind of thermometer would you use for measuring the temperature of a COVID patient?
Answer:
Infrared thermometer.

10. What scale of temperature is used in scientific work?
Answer:
Kelvin scale.

11. Convert 25 ^oC to Kelvin.
Answer:
Temperature in Kelvin scale = Temperature in Celsius scale + 273.15

Therefore, in this case temperature in Kelvin scale = 25 + 273.15 = 298.15 ^oC.

12. Name a way in which fever was detected before thermometers were developed.
Answer:
Fever was detected using pulse rate of a person before thermometers were developed.

13. What liquids are used in a laboratory thermometer?
Answer:
Alcohol or mercury.

14. Do all laboratory thermometers have the same scale?
Answer:
No, different laboratory thermometers can have different scales.

Short Answer Type Questions:

1. Why should the thermometer not be held by the bulb while reading it?
Answer:
The thermometer should not be held by the bulb because the heat from the hand might cause the mercury in the thermometer to further expand, thereby changing the reading.

2. Why should the thermometer be read keeping the level of mercury along the line of sight?
Answer:
The thermometer should be read keeping the mercury level along the line of sight to avoid getting the wrong reading. If the viewing angle is not perpendicular to the position of the eye, you will get a wrong reading as shown in the diagram below:

This is called parallax error.

3. How many divisions should a thermometer have?
Answer:
If a thermometer has too few divisions, you will have trouble getting an accurate reading. On the other hand, too many divisions are redundant – you do not need too many divisions to get an accurate reading. Therefore, the number of divisions should not be too few or too many.

4. Is the normal human body temperature always 37⁰ C?
Answer:
The normal human body temperature isnot necessarily = 37⁰ C. The human body temperature fluctuates from time to time and can be slightly higher or slightly lower than 37⁰ C. We say that 37⁰ C is the average human body temperature because that is the average body temperature of a large number of healthy people. However, it may vary from time-to-time and from person-to-person.

5. Why is the range of a clinical thermometer between 35⁰ C and 42⁰ C?
Answer:
The human body temperature normally varies between a low of 35⁰ C and a high of 42⁰ C. It does not usually go beyond that range. Therefore, choosing a range greater than 35 – 42⁰ C would be redundant.

6. Name two of the hottest and two of the coldest places in India.
Answer:
Two of the hottest places in India are Phalodi and Churu, both in Rajasthan. Two of the coldest places in India are Dras and Siachen Glacier, both in Ladakh.

7. What are the highest and lowest temperatures that can exist?
Answer:
There is no limit on the highest temperature that can exist. However, as per scientific understanding, there is a limit to the lowest temperature that can be achieved. It is close to –273.15 °C (0 kelvin) and is called absolute zero.

8. Who was known as the ‘Weather Woman of India’? Describe her contributions in brief.
Answer:
Anna Mani (1918–2001) was an Indian scientist who was as the ‘Weather Woman of India’. She invented and built a large number of weather measurement instruments. This reduced the reliance of India on other nations for such instruments. She also explored the possibilities of using wind and solar energy in India, which helped India to become one of the global leaders in renewable energy.

9. Suppose you measure the temperature of ice in a beaker using a laboratory thermometer. What will it indicate? Then suppose you measure the temperature after some of the ice has melted into water. What is the temperature now? What does this indicate? What happens if you keep heating the ice for a long period of time?
Answer:
Initially the temperature of the ice will read 0^oC. After some ice has melted into water, the temperature will still read 0^oC. This indicates that the temperature of ice remains constant while it is melting. If you keep heating the ice for a long period of time, it completely changes into water and then on continued heating, it evaporates to form steam.

Long Answer Type Questions:

1. What are advantages of a digital thermometer over a mercury thermometer?

Answer: The advantages of a digital thermometer over a mercury thermometer are:

(i) It is simple and convenient to use.

(ii) Digital thermometers give instant readings because it does not have to wait for the mercury to rise up.

(iii) It does not contain toxic mercury and is safer to use. If it breaks there is no danger.

(iv) It gives more precise readings than mercury thermometers. 

Fill in the Blanks:

Kelvin, increases, summer, 37 ^oC, winter, decreases

(a) The body temperature of the average healthy person fluctuates around __________.

(b) The air temperature in ________ is higher than the air temperature in __________.

(c) The SI unit of temperature is _________.

(d) During vigorous exercise the body temperature __________.

(e) During sleeping body temperature typically __________.

Answers:

(a) The body temperature of the average healthy person fluctuates around 37 ^oC.

(b) The air temperature in summer is higher than the air temperature in winter.

(c) The SI unit of temperature is Kelvin.

(d) During vigorous exercise the body temperature increases.

(e) During sleeping body temperature typically decreases.

Match and Pair:

Column I	Column II
(i) Laboratory thermometer	(a) 100 °C
(ii) Clinical thermometer	(b) 0 oC
(iii) Temperature of boiling water	(c) –10 °C to 110 °C
(iv) Melting point of ice	(d) 15 million degrees Celsius
(v) Temperature of core of Sun	(e) 35 °C to 42 °C

Answer:

Column I	Column II
(i) Laboratory thermometer	(c) –10 °C to 110 °C
(ii) Clinical thermometer	(e) 35 °C to 42 °C
(iii) Temperature of boiling water	(a) 100 °C
(iv) Melting point of ice	(b) 0 oC
(v) Temperature of core of Sun	(d) 15 million degrees Celsius

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