Q1.
Following two experimental setups are to be arranged by your teacher. One by one, as per your turn, go closer to the setups and observe the readings of both the thermometers. What are the temperatures of ice and boiling water?
Answer
Read the two laboratory thermometers, keeping your eye in line with the top of each liquid column.
| Setup | What the thermometer shows |
|---|---|
| Crushed ice (melting) | about 0 °C |
| Boiling water | about 100 °C |
These are the standard values at sea level. In your own classroom the boiling water may read a little less than 100 °C.
Why boiling water may not reach 100 °C: water boils at 100 °C only under normal air pressure at sea level. Higher up a hill the air pressure is lower and water boils at a lower temperature. That is why Phiban and her classmates in Shillong — a hill town — recorded about 98 °C for boiling water in Activity 7.6, not 100 °C.
Caution: This activity must be done strictly under the supervision of the teacher. Do not touch the experimental setups.