1. What is heat?
Ans: Heat is a form of energy which gives the sensation of warmth.
According to molecular theory, heat is the sum of total kinetic energy of vibrating molecules.
2. What is convection?
Ans: The process of transfer of heat in liquids by the actual movement of molecules is called convection.
3. What is radiation?
Ans: The process of transmission of heat without any media is called radiation.
4. What is 1 calorie?
Ans: 1 calorie is the amount of heat required to raise the temperature of 1 gram of water by 1°C.
5. What is thermometer?
Ans: An instrument used to measure the temperature of body is called themometer.
6. What is clinical thermometer?
Ans: The instrument used to measure the temperature of human body is called clinical thermometer.
7. What is temperature?
Ans: The degree of hotness and coldness of a body is called temperature.
8. What is anomalous expansion of water?
Ans: The property of water in which water contracts on heating from 0°C to 4°C and then expands on further heating from 4°C is called anamolous expansion of water.
9. What is lower fixed point?
Ans: The temperature of the pure melting ice at normal pressure is called lower fixed point.
10. What is upper fixed point?
Ans: The temperature of the pure boiling water at normal pressure is called upper fixed point.
11. What is the working principle of thermometer?
Ans: The working of the thermometer is based on the principle that “when a body is heated, it expands and contracts on cooling”.
12. What is laboratory thermometer?
Ans: The thermometer used for measuring the temperature of different bodies is called laboratory thermometer.
13. What is maximum and minimum thermometer?
Ans: The thermometer used to measure the maximum and minimum temperatures within twenty four hours is called maximum and minimum thermometer.
14. What are the commonly used liquids in thermometer?
Ans: Alcohol and mercury are the commonly used liquids in thermometer.
15. What is Celsius scale?
Ans: The scale in which upper fixed point is taken as 100°C and lower fixed pont is 0°C is called celcius scale.
16. What is heat? Write two reasons of using mercury in a thermometer.
Ans: Heat is a form of energy which flows from a hotter body to a colder body.
The reasons for using mercury in a thermometer is are as followings:
I. It is a good conductor of heat.
II.It is silvery white in colour, therefore, it can be seen easily in glass.
17. Write two differences between heat and temperature.
Ans: Differences between heat and temperature are as followings:
| Heat | Temperature |
| It is a form of energy that gives sensation of warmth. | It is the degree of hotness and coldness of a body. |
| It is a cause of change of temperature. | It is an effect of heat. |
18. At what temperature Celsius and Fahrenheit are equal. Show by calculation.
Ans: Do yourself.
19. Alcohol thermometer cannot be used to measure the boiling point of water, why?
Ans: Alcohol thermometers are filled with alcohol. Water has boiling point 100ᵒC. The boiling point of alcohol is 78ᵒC, so alcohol thermometer cannot measure the temperature greater than 78ᵒC. Hence,alcohol thermometer cannot be used to measure the boiling point of water.
20. Telephone wires sag in summer, why? Write the boiling and freezing point of alcohol.
Ans: Telephones wires are made up of copper. Copper is a metal and metals get expanded when heated and contracted when cooled. In summer due to higher temperature, copper wires are expanded and in winter due to lower temperature, copper wires are contracted.So, telephone wires sag in summer.
The boiling and freezing point of alcohol is 78ᵒC and -117ᵒC respectively
21. Name any two thermometric liquid that are used in thermometer. Write any two differences between clinical and laboratory thermometer.
Ans: Thermometric liquid used in thermometer are as followings:
• Mercury
• Alcohol
The differences between clinical thermometer and laboratory thermometer are as followings:
| Clinical thermometer | Laboratory thermometer |
| Clinical thermometer is scaled from 35ᵒC to 42ᵒC or from 94ᵒF to 108ᵒF. | Laboratory thermometer is generally scaled from -10ᵒC to 110ᵒC. |
| Clinical thermometer is used to take body temperature. | Laboratory thermometer is used to take the temperature of laboratory. |
22. Convert 200oC into oF.
(Do yourself)
23. Write the reasons of using alcohol in the thermometer? Mountaineers use alcohol thermometer. Why?
Ans: The reasons of using alcohol in the thermometer are as followings:
• Its expansion rate is about seven times more than that of mercury, which makes the thermometer more sensitive.
• It's cheaper than mercury
The freezing point for alcohol is -117ᵒC and the freezing point for mercury is -39ᵒC. So, alcohol thermometer is appropriate to measure temperatures in cold places as compared to mercury thermometer. Hence, mountaineers use alcohol thermometer.