NCERT Solutions Curiosity Chapter 7 .1 Hot or Cold? / 7.2 Temperature — In-text Questions

Book page 1257 Updated on2026-09-05

Q1.
Compare whether your observations match with your predictions. Did your right hand feel that the water in container B is cool, while your left hand felt that the same water is warm? What do you infer from these observations?
Answer

Yes — the observations match the predictions. The right hand felt B cool and the left hand felt the same water warm.

The inference:

The same water gave two different answers at the same moment.
Therefore the feeling of hotness depends on the hand, not only on the water.
We cannot always rely upon our sense of touch to decide whether a body is hot or cold.
Why this matters in science: a measurement must give the same result no matter who takes it. Touch fails this test, so science needs an instrument and a number — a thermometer and a temperature in °C.
Q2.
Then how do we find out how hot or cold a body is?
Answer

By measuring its temperature with a thermometer.

  • Temperature is a reliable measure of the hotness (or coldness) of a body.
  • A hotter body has a higher temperature than a colder body.
  • The difference in temperature between two bodies tells us how much hotter one is than the other.
  • The device that measures temperature is called a thermometer.

You will meet two kinds in this chapter:

ThermometerUsed for
Clinical thermometerHuman body temperature
Laboratory thermometerMany other purposes — water, air, chemicals
Tip: “Hot” and “cold” are opinions; “42.5 °C” is a measurement. Science prefers the second.
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