Question

D. LONG-ANSWER QUESTIONS: Answer in about 50 words.
(1. Explain why a substance expands on heating.
2. Give one example where expansion on heating is put to good use. Explain the working with
the help of a labelled diagram.
3. Explain why gases expand more than liquids and solids.
4. Explain with the help of a labelled diagram an experiment to show that liquids expand when
heated.
5. Expansion on heating can be a nuisance. Explain giving two examples.
6. Convert: 25 °C to ⓇF and 86 °F to °C
7. Calculate the temperature at which the reading on the Fahrenheit scale is double the reading
on the Celsius scale.
8. What precautions will you take while measuring temperature with a laboratory
thermometer? What extra precaution will you
take while measuring
body temperature with a
clinical thermometer?
​

Answer 1

Answer:

1. When heat is added to a substance, the molecules and atoms vibrate faster. As atoms vibrate faster, the space between atoms increases. The motion and spacing of the particles determines the state of matter of the substance, thus causing a substance to get expanded.
2. In fire alarm expansion put in good use. The alarm contains two strips of iron and
3. Gases expand more than liquids and solids because the molecules of gases because the molecules of gases are seperated from one another by wide spaces. When gas is heated (heat is a form of energy) its molecules began to vibrate fast and as a result begins to move away from each other.
4. Take a test tube completely filled with coloured water, such that in its mouth is fixed a stopper containing a long glass tube.  Let the level of liquid in glass tubing be at A. Place the test tube in a beaker, containing boiling hot water.  It is observed that first level of water falls to B and then rises up to C.  The fall in level of liquid can be attributed to the fact that initially only the glass tube, being in direct contact with the water bath, expands; but not the water. However, the level of liquid rises to C, when liquid starts expanding. Thus, experiment proves: Liquids expand on heating  , Since BC > AB, liquids expand more than solids for the same rise in temperature.
5. In the summer wires expand due to heat making them loose thus making loss of power more common.

• Expanding of train tracks which leads to derailing of the train, that is why fish plates are added in the tracks to help prevent this .

1. 25 °c to °F is 77 °F and 86 °F to °C is 30 °C.

I hope this helps you!