A. Short-Answer Questions:
1. How can you say that hot air is lighter than cold air?
2. What is the function of the kink in a thermometer?
3.Containers carrying petrol and diesel are coated with insulators. Give reason.
4. Name the common liquids with which thermometers are filled. What precautions should you take while handling a thermometer?
5. Explain briefly with the help of an activity that the amount of heat absorbed by an object depends on its colour.
Answers
Answer:
1)Hot air is lighter than cold air. The reason fr this is when air gets heated up it expands and becomes less dense than the air surrounding it also the distance between the molecules increases. So the less dense air floats in the much denser air just like ice floats on water as ice is less dense than water.
2)The kink breaks the mercury ensuring that the mercury isn't sucked back into the bulb allowing the temperature to be read. Before it can be used again the thermometer has to be shaken to force the mercury back down and remove the break.
3)Petrol and diesel have a tendency to catch fire (spontaneous combustion) when it's in contact with a little high temperature.... Therefore containers carrying petrol and diesel are coated with insulators so that the temperature inside the container would be less....
4)For this reason, a common form of thermometer contains a liquid in a narrow glass tube. Mercury is one of the most familiar materials used in liquid thermometers. Other liquids, such as kerosene or ethanol, may also be used in these types of thermometers
5)Dark colors, especially black, absorb more heat since they'll absorb more light from the environment. If you're trying to stay cool, wear light colors, which absorb less heat.
Answer:3.Petrol and diesel have a tendency to catch fire (spontaneous combustion) when it's in contact with a little high temperature.... Therefore containers carrying petrol and diesel are coated with insulators so that the temperature inside the container would be less
4. mercury is a common liquid filled in thermometers.
Following precautions must be followed while handling the thermometers: Wash the thermometer and dip it into an antiseptic liquid before and after use.