Essential Science Q&A: Temperature, Thermometers, and Space Facts

Part I: Temperature and Thermometers

Basic Concepts and Scales

1. Name the Three Scales of Temperature.

Ans: The three scales of temperature are:

• Celsius
• Fahrenheit
• Kelvin

2. How Are Temperature and Hotness Related?

Ans: Temperature and hotness of a body are directly related. The hotter a substance is, the higher its temperature.

3. Reading a Laboratory Thermometer: Eye Level Precaution

Ans: While reading the temperature on a laboratory thermometer, the eye must be at the level of the mercury in the stem to avoid parallax error and ensure an accurate reading.

4. How Does a Digital Thermometer Measure Temperature?

Ans: A digital thermometer does not use mercury. It utilizes internal heat sensors (such as a thermistor or thermocouple) to measure the temperature electronically.

True or False Statements on Thermometry

5. A traditional clinical thermometer has a kink in its stem.

Ans: True

(The kink prevents the mercury level from falling immediately when the thermometer is removed from the mouth, allowing time for reading.)

6. Is the Boiling Point of Pure Water Constant Globally?

Ans: False

The boiling point of pure water is 100°C at sea level and decreases as altitude increases (due to lower atmospheric pressure).

7. Laboratory Thermometer Range: 0°C to 100°C?

Ans: False

Commonly used laboratory thermometers are marked from –10°C to 110°C.

8. Formula for Celsius to Fahrenheit Conversion

To convert Celsius (C) to Fahrenheit (F), we use the formula: F = (9/5 × C) + 32.

Ans: True

9. Lower Fixed Points of Celsius and Fahrenheit Scales

Ans: False

The lower fixed point in Celsius is 0°C, but in Fahrenheit it is 32°F.

10. Digital Clinical Thermometers and Mercury Use

Ans: True

A digital clinical thermometer does not contain mercury, making it safer than traditional glass thermometers.

Detailed Questions on Temperature Measurement

1. Are 'Cool' and 'Warm' Relative Terms? Explain with an Experiment.

Ans: Yes, 'cool' and 'warm' are relative terms that depend entirely on the situation and the reference point of the observer. This can be demonstrated by the following experiment:

Experiment:

1. Take three vessels: one with ice-cold water, one with warm water, and one with normal tap water.
2. Dip the left hand in cold water and the right hand in warm water for one minute.
3. Now, dip both hands simultaneously into the normal tap water.

Observation:

• The left hand (coming from cold water) will feel the tap water is warm/hot.
• The right hand (coming from warm water) will feel the tap water is cold.

Conclusion: This experiment shows that sensations of 'cool' and 'warm' are relative and are based on the temperature difference relative to the skin's previous exposure.

2. Temperature Conversion Calculations (Celsius and Fahrenheit)

Convert:

1. 25°C to °F
2. 86°F to °C

(a) 25°C to °F

F = (9/5 × C) + 32
F = (9/5 × 25) + 32
F = (9 × 5) + 32
F = 45 + 32 = 77°F

(b) 86°F to °C

C = (5/9) × (F – 32)
C = (5/9) × (86 – 32)
C = (5/9) × 54
C = 5 × 6
C = 30°C

3. Precautions for Using a Laboratory Thermometer

Ans: Key precautions to take while measuring temperature with a laboratory thermometer include:

• The thermometer should be washed thoroughly before and after use.
• It must be handled with care to prevent breakage, especially the glass bulb.
• It should be held by the stem, avoiding contact with the bulb during measurement.
• The bulb must be completely surrounded by the substance whose temperature is being measured.
• While reading the thermometer, the eye should be positioned exactly at the level of the mercury meniscus to ensure accuracy.

4. Differences Between Laboratory and Digital Thermometers

Ans:

Part II: Chapter 12 – Beyond the Earth (Astronomy Basics)

Quick Facts on Constellations and Planets

1. Definition of a Constellation

Ans: Yes, a constellation is a recognizable pattern or grouping of stars in the night sky.

2. Our Home Galaxy

Ans: We live in the Milky Way Galaxy.

3. Constellation of the Big Dipper

Ans: The Big Dipper (or Plough) is an asterism located within the Ursa Major constellation (The Great Bear).

4. Constellation Shaped Like a Hunting Man

Ans: The constellation Orion forms the shape of a hunting man.

5. Key Facts About Solar System Planets

Ans:

1. Largest planet – Jupiter
2. Planet closest to the Sun – Mercury
3. Red planet – Mars
4. Farthest planet from the Earth – Neptune