NCERT Solutions for Class 6 Science Chapter 07 Temperature and its Measurement

 

Question 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
Answer: (ii) 37.0 °C
In simple words: A healthy person's body temperature stays around 37 degrees Celsius, which is warm but not hot.

Exam Tip: Remember that 37°C is the standard human body temperature - this is a key fact that appears in many questions about thermometers.

 

Question 2. 37 °C is the same temperature as _______.
(i) 97.4 °F
(ii) 97.6 °F
(iii) 98.4 °F
(iv) 98.6 °F
Answer: (iv) 98.6 °F
In simple words: When you convert 37 degrees Celsius to Fahrenheit, you get 98.6 degrees Fahrenheit - this is the normal body temperature.

Exam Tip: Use the formula °F = (°C × 9/5) + 32 to convert between temperature scales quickly.

 

Question 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 _______.
Answer:
(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.
In simple words: Temperature tells us how hot or cold something is. A clinical thermometer is used for bodies, not cold water. We measure temperature in degrees Celsius.

Exam Tip: Know which thermometer is used for which purpose - clinical thermometers have a narrow range, while lab thermometers cover a wider range.

 

Question 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
Answer: (ii) -10 °C to 110 °C
In simple words: A laboratory thermometer can measure very cold and very hot things, from minus 10 degrees up to 110 degrees Celsius.

Exam Tip: Clinical thermometers measure only body temperature (35-42°C), but laboratory thermometers have a much wider range.

 

Question 5. Four students used a laboratory thermometer to measure the temperature of water as shown in Figure:
Answer: The correct way to measure the temperature using a laboratory thermometer is shown by Student 2. Student 2 has the thermometer placed straight down into the water without letting it touch the sides or the bottom of the container, which is the proper method for measuring temperature with a laboratory thermometer.
In simple words: Hold the thermometer straight in the water, away from the sides and bottom of the cup, to get the right reading.

Exam Tip: Always keep the thermometer vertical and not touching the container walls - this gives you an accurate reading of the water's true temperature.

 

Question 6. Colour to show the red column on the drawings of thermometers (See Figure) as per the temperatures written below:
Answer: The red column in each thermometer should be coloured to show the following levels:
- First thermometer: Colour the red column up to the 14°C mark
- Second thermometer: Colour the red column up to the 17°C mark
- Third thermometer: Colour the red column up to the 7.5°C mark
In simple words: For each thermometer, shade the red liquid inside so it reaches the temperature shown above it.

Exam Tip: Make sure you colour the red column carefully up to exactly the right mark - being precise helps show you understand how to read a thermometer.

 

Question 7. Observe the part of thermometer shown in Figure 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?
Answer:
(i) This is a laboratory thermometer, which has a long, thin tube and a scale that goes beyond the normal human body temperature range.
(ii) The thermometer reading is 15.4°C. You can find this by looking at where the red liquid level sits - it is just above the 15°C mark, with four small divisions (each worth 0.1°C) above it.
(iii) The smallest value that this thermometer can measure is - 10°C. The small divisions between the larger degree marks, each representing 0.1°C, allow for very precise readings.
In simple words: This is a laboratory thermometer that can read very hot and very cold temperatures. The red liquid shows 15.4 degrees. The thermometer can measure down to minus 10 degrees.

Exam Tip: Always look carefully at the small divisions on a thermometer - each tiny line often represents 0.1°C, which is why you need to read between the main numbers.

 

Question 8. A laboratory thermometer is not used to measure our body temperature. Give a reason.
Answer: A laboratory thermometer is not used to measure body temperature because it is made to measure temperatures over a very wide range. It must be held straight up, which makes it awkward and sometimes unsafe for measuring body temperature. Clinical thermometers are built differently - they are smaller and designed only for the narrow temperature range of the human body, making them much easier and safer to use.
In simple words: Laboratory thermometers are too long and measure too many temperatures. We need a special small thermometer for bodies that only measures the right temperature range.

Exam Tip: When asked why a lab thermometer cannot be used for body temperature, mention both the wide range it measures and the inconvenience of holding it upright.

 

Question 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

Answer:
(i) Vaishnavi's highest recorded temperature was 40.0°C.
(ii) Vaishnavi's highest temperature was recorded on Day One at 7 pm.
(iii) Vaishnavi's temperature returned to normal on Day Three.
In simple words: On the first day, her fever reached the highest point of 40 degrees at 7 in the evening. By the third day, her temperature came back down to normal.

Exam Tip: When reading data from a table, look carefully at both the row (day) and column (time) to give a complete answer about when something happened.

 

Question 10. If you have to measure the temperature 22.5 °C, which of the following three thermometers will you use (See Figure)? Explain.
Answer: To measure the temperature of 22.5°C, you should select thermometer (c).

Looking at each thermometer:
- Thermometer (a): This thermometer has a range from 0°C to 30°C, with divisions that allow for precise measurements. However, it does not have enough resolution to read 0.5°C intervals clearly.
- Thermometer (b): This thermometer has a range from -10°C to 50°C and has divisions that indicate smaller intervals, possibly 0.2°C or 0.1°C. It seems to have a finer scale and can accurately measure 22.5°C.
- Thermometer (c): This thermometer has a range from -10°C to 110°C and has even finer divisions, which can accurately measure 22.5°C.

Conclusion: Thermometer (c) is the best choice because it has a wider range and finer divisions, allowing for precise readings, including 22.5°C. Explanation: Thermometer (c) allows for the precise measurement of 0.5°C intervals, making it suitable for accurately determining a temperature of 22.5°C.
In simple words: Thermometer (c) works best because it has very small divisions that let you read 0.5 degrees accurately. The tiny marks on the scale let you find 22.5 degrees exactly.

Exam Tip: Choose a thermometer by checking two things: first, does it cover the temperature you need to measure? Second, are its divisions small enough to read that temperature precisely?

 

Question 11. The temperature shown by the thermometer in Figure is
(i) 28.0 °C
(ii) 27.5 °C
(iii) 26.5 °C
(iv) 25.3 °C
Answer: (ii) 27.5 °C
In simple words: Look at where the red liquid reaches on the scale. It sits halfway between 27 and 28, which means it shows 27.5 degrees.

Exam Tip: When the red liquid level falls between two main numbers, estimate the position carefully - if it is exactly in the middle, the reading is 0.5 degrees above the lower number.

 

Question 12. A laboratory thermometer has 50 divisions between 0°C and 100°C. What does each division of this thermometer measure?
Answer: A laboratory thermometer with 50 divisions between 0°C and 100°C means each division represents a specific temperature increment. To determine the value of each division, divide the total temperature range by the number of divisions. Here, the range is 100°C (from 0°C to 100°C) and there are 50 divisions. Therefore, each division measures:
Value of each division = 100°C/50 = 2°C
Thus, each division on this laboratory thermometer represents 2°C. This allows for measurements to be read with an accuracy of 2°C increments.
In simple words: You have 100 degrees to divide among 50 small lines. Each line stands for 2 degrees. So when the red liquid moves up one small line, the temperature goes up by 2 degrees.

Exam Tip: Always use division = total range ÷ number of divisions. This formula works for any thermometer and helps you find the precision of any scale.

 

Question 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.
Answer: A thermometer scale with 0.5°C divisions between 10°C and 20°C would show major marks at every degree (10°C, 11°C, 12°C, and so on) with smaller division marks between each degree. Each smaller division represents 0.5°C. The scale would look like this: at 10°C there is a mark, then a smaller mark at 10.5°C, then another at 11°C, and this pattern continues through 20°C. The numbered labels appear only at the whole degrees (10, 11, 12... 20).
In simple words: Draw a line with big marks at 10, 11, 12 degrees and so on up to 20. Between each big mark, put one small mark exactly in the middle. Each small mark means plus 0.5 degrees.

Exam Tip: When drawing thermometer scales, always ensure equal spacing between marks and label the main degree marks clearly while showing smaller divisions between them.

 

Question 14. Someone tells you that she has a fever of 101 degrees. Does she mean it on the Celsius scale or Fahrenheit scale?
Answer: If someone tells you that she has a fever of 101 degrees, she means it on the Fahrenheit scale. A body temperature of 101 degrees Fahrenheit indicates a fever, as the normal human body temperature is approximately 98.6°F. In Celsius, 101 degrees would be extremely high and life-threatening, since normal body temperature is around 37°C and 101°C is far beyond what any living being could survive. Therefore, it is clear that the fever is being referred to in Fahrenheit.
In simple words: 101 degrees must be in Fahrenheit because it is slightly above normal body temperature. If it were 101 degrees Celsius, that person would be dead - it is way too hot!

Exam Tip: Always think about whether the number makes sense - 101°F is a high fever but alive; 101°C is impossible for a living person.