Chapter Exercises: Let us Enhance our Learning

Multiple Choice & Short Answer Questions

1. Normal Human Temperature

The normal temperature of a healthy human being is close to: (i) $98.6^{\circ}\text{C}$ (ii) $37.0^{\circ}\text{C}$ (iii) $32.0^{\circ}\text{C}$ (iv) $27.0^{\circ}\text{C}$

Answer: (ii) $37.0^{\circ}\text{C}$

Explanation: The normal human body temperature is defined as $37.0^{\circ}\text{C}$ on the Celsius scale. Option (i) is the value in Fahrenheit, but the unit shown is Celsius, which would be fatal.

2. Celsius to Fahrenheit

$37^{\circ}\text{C}$ is the same temperature as: (i) $97.4^{\circ}\text{F}$ (ii) $97.6^{\circ}\text{F}$ (iii) $98.4^{\circ}\text{F}$ (iv) $98.6^{\circ}\text{F}$

Answer: (iv) $98.6^{\circ}\text{F}$

Explanation: This is the standard conversion for normal body temperature.

3. Fill in the Blanks

(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.

Reason: A clinical thermometer typically ranges from $35^{\circ}\text{C}$ to $42^{\circ}\text{C}$, while ice-cold water is near $0^{\circ}\text{C}$. (iii) The unit of temperature is degree Celsius (or Fahrenheit). Note: The SI unit is kelvin, but the blank includes the word ‘degree’, implying Celsius or Fahrenheit.

4. Laboratory Thermometer Range

The range of a laboratory thermometer is usually: (i) $10^{\circ}\text{C}$ to $100^{\circ}\text{C}$ (ii) $-10^{\circ}\text{C}$ to $110^{\circ}\text{C}$ (iii) $32^{\circ}\text{C}$ to $45^{\circ}\text{C}$ (iv) $35^{\circ}\text{C}$ to $42^{\circ}\text{C}$

Answer: (ii) $-10^{\circ}\text{C}$ to $110^{\circ}\text{C}$

5. Correct Usage Diagram

Reference to Fig 7.6 in textbook showing 4 students measuring water temperature.

• Student 1: Holds it diagonally, touching the side.
• Student 2: Bulb touches the bottom.
• Student 3: Bulb suspended in water, held vertically.
• Student 4: Bulb not fully immersed.

Question: Who followed the correct way? Answer: (iii) Student 3

Explanation: The thermometer must be held vertically and the bulb must be immersed in the water without touching the bottom or sides of the container.

6. Coloring the Thermometer

This is a visual activity.

• $14^{\circ}\text{C}$: Mark 4 small divisions above 10.
• $17^{\circ}\text{C}$: Mark 7 small divisions above 10.
• $7.5^{\circ}\text{C}$: Mark exactly between the 7th and 8th division above 0 (assuming 1 division = 1 degree).

7. Reading the Thermometer (Fig 7.8)

(i) Type: This is a Laboratory Thermometer (based on the markings typically shown in such diagrams). (ii) Reading: Assuming the image shows a specific level. If the level is at the 2nd small mark after 20, it is $22^{\circ}\text{C}$. (iii) Smallest Value: Look at the divisions. If there are 10 divisions between $0$ and $10$, the smallest value is $1^{\circ}\text{C}$.

8. Lab Thermometer for Body Temp?

Question: A laboratory thermometer is not used to measure our body temperature. Give a reason. Answer: A laboratory thermometer does not have a “kink” or constriction near the bulb. Therefore, as soon as it is taken out of the mouth (or armpit), the liquid level falls due to cooling. This makes it impossible to get an accurate reading of the body temperature outside the body.

9. Vaishnavi’s Temperature Record

Table Data Analysis:

• Day 1 High: $40.0^{\circ}\text{C}$ (7pm)
• Day 2 High: $39.0^{\circ}\text{C}$ (1pm, 4pm, 7pm)
• Day 3 High: $37.6^{\circ}\text{C}$ (7am)

(i) Highest recorded: $40.0^{\circ}\text{C}$. (ii) When: Day One at 7 pm. (iii) Return to normal: On Day Three, the temperature dropped to $37.0^{\circ}\text{C}$ at 4 pm and continued to drop/stabilize. $37.0^{\circ}\text{C}$ is normal.

10. Choosing a Thermometer for $22.5^{\circ}\text{C}$

Three thermometers shown in Fig 7.9 (presumably with different Least Counts).

• (a) Divisions of 1 degree ($0, 1, 2...$). Can read $22$ or $23$.
• (b) Divisions of 0.5 degrees ($0, 0.5, 1...$). Can read $22.5$.
• (c) Divisions of 2 degrees ($0, 2, 4...$). Hard to read $22.5$.

Answer: Thermometer (b).

Reason: To measure $22.5^{\circ}\text{C}$ accurately, we need a thermometer with a least count (smallest division) of at least $0.5^{\circ}\text{C}$.

11. Reading Fig 7.10

Image typically shows marks between 20 and 30. If there are 10 divisions between 20 and 30, each is $1^{\circ}\text{C}$. If the reading is at the 6th mark after 20: $26^{\circ}\text{C}$. Looking at the options provided in the text question: (i) 28.0 (ii) 27.5 (iii) 26.5 (iv) 25.3. Without the exact image, we check the scale. If the scale is between 20 and 30 with 2 degree increments? Or 0.5? Let’s assume the question implies reading between marks. If the specific answer key points to 27.5°C, the liquid must be exactly halfway between 27 and 28.

12. Least Count Calculation

Given: 50 divisions between $0^{\circ}\text{C}$ and $100^{\circ}\text{C}$. Calculation: $\text{Value of 1 division} = \frac{\text{Total Range}}{\text{Number of Divisions}}$ $\text{Value} = \frac{100 - 0}{50} = \frac{100}{50} = 2^{\circ}\text{C}$ Answer: Each division measures $2^{\circ}\text{C}$.

13. Drawing a Scale

Task: Draw scale between $10^{\circ}\text{C}$ and $20^{\circ}\text{C}$ with smallest division $0.5^{\circ}\text{C}$. Description: Between 10 and 11, there should be one mark in the middle (representing 10.5). So between 10 and 20 (a gap of 10), there should be $10 \times 2 = 20$ divisions total.

14. Komal’s Fever

Question: Komal has a fever of 101 degrees. Celsius or Fahrenheit? Answer: She means Fahrenheit ($^{\circ}\text{F}$).

Reason: $101^{\circ}\text{C}$ is above the boiling point of water; a human would not survive. $101^{\circ}\text{F}$ is a common fever temperature (approx $38.3^{\circ}\text{C}$).