class vi science 3

10 FILL IN THE BLANKS

1. A reliable measure of hotness (or coldness) of a body is its temperature.
2. A device that measures temperature is called a thermometer.
3. The two kinds of thermometers discussed are clinical thermometers and laboratory thermometers.
4. Clinical thermometers are used to measure human body temperatures.
5. The normal temperature of a healthy human body is taken to be 37.0 °C.
6. Digital clinical thermometers run on batteries.
7. The temperature of human beings does not normally go below 35 °C or above 42 °C.
8. The SI unit of temperature is kelvin.
9. Laboratory thermometers typically have a temperature range from –10 °C to 110 °C.
10. Non-contact thermometers are also called infrared thermometers.

05 COMPETENCY BASED QUESTIONS WITH ANSWERS

1. Scenario Analysis (Sense of Touch): A student places one hand in warm water and the other in ice-cold water, then both hands in tap water. What is observed and what concept does this show?
   Answer:
   The hand coming from warm water feels the tap water cool, while the hand coming from ice-cold water feels it warm. This shows that our sense of touch is not reliable, and a correct measure like temperature is required.
2. Application / Precaution: Why should a laboratory thermometer be read while immersed in the substance?
   Answer:
   When taken out, the liquid column falls immediately. Therefore, the reading must be taken while the thermometer is still immersed to get an accurate temperature.
3. Reasoning: Why have digital thermometers replaced mercury thermometers?
   Answer:
   Mercury is toxic and dangerous if the thermometer breaks. Digital thermometers are safer and easier to read.
4. Comparison: Why can a clinical thermometer not measure boiling water or ice?
   Answer:
   Clinical thermometers work only between 35 °C and 42 °C, which is unsuitable for boiling water or ice.
5. Procedure: What care must be taken while washing a digital thermometer?
   Answer:
   The digital display should not get wet, and the thermometer should not be held by the tip.

05 IMPORTANT QUESTIONS (NO ANSWERS)

1. Define temperature and explain how a hotter body differs from a colder body.
2. Write the formula to convert Celsius temperature into Kelvin.
3. Which physical change in the human body was traditionally used to detect fever in India, and why is it unreliable?
4. Differentiate between clinical and laboratory thermometers.
5. Explain how to calculate the least count of a laboratory thermometer.