Question 1: State similarities and differences between the laboratory thermometer and the clinical thermometer.
|Clinical Thermometer||Laboratory Thermometer|
|The range of clinical thermometer is from 35°C to 42°C or from 94°F to 108°F.||The range of laboratory thermometer is from -10°C to 110°C.|
|Mercury level does not fall on its own, as there is a kink near the bulb to prevent the fall of mercury level.||Mercury level falls on its own as no kink is present.|
|Temperature can be read after removing the thermometer from armpit or mouth.||Temperature is read while keeping the thermometer in the source of temperature, e.g. a liquid or any other thing.|
|To lower the mercury level jerks are given.||No need to give jerk to lower the mercury level.|
|It is used for taking the body temperature.||It is used to take temperature in laboratory.|
Question 2: Give two examples each of conductors and insulators of heat.
Answer: Examples of conductor: Iron, copper
Examples of insulator: Rubber, plastic
Question 3: Fill in the blanks:
Answer: (a) temperature, (b) clinical thermometer Dark, (c) Celsius, (d) Radiation, (e) Conduction, (f) dark
Question: 4 - Match the following:
|Column A||Column B|
|(1) Land breeze blows during||(a) Summer|
|(2) Sea breeze blows during||(b) Winter|
|(3) Dark coloured clothes are preferred during||(c) Day|
|(4) Light coloured clothes are preferred during||(d) Night|
Answer: (1) d, (2) c, (3) b, (4) a
Question 5: Discuss why wearing more layers of clothing during winter keeps us warmer than wearing just one thick piece of clothing?
Answer: By wearing more layers of clothing, air gets trapped between different layers. This makes different layers of insulation and thus provides better protection against cold. On the other hand, wearing just one piece of clothing creates just one insulator layer and hence is less effective in beating the cold.
Question 6: Look at Fig. 4.13 (in NCERT Text Book). Mark where the heat is being transferred by conduction, by convection and by radiation.
Question 7: In places of hot climate it is advised that the outer walls of houses be painted white. Explain.
Answer: White colour reflects most of the heat falling on it. This makes the house colder. Thus, in places of hot climate it is advised that the outer walls of house be painted white.
Question 8: One litre of water at 30°C is mixed with one litre of water at 50°C. The temperature of the mixture will be
Answer: (d) between 30°C and 50°C
Question 9: An iron ball at 40°C is dropped in a mug containing water at 40°C. The heat will
Answer: (b) not flow from iron ball to water or from water to iron ball.
Question 10: A wooden spoon is dipped in a cup of ice cream. Its other end
Answer: (d) does not become cold.
Question: 11: Stainless steel pans are usually provided with copper bottoms. The reason for this could be that
Answer: (c) Copper is a better conductor of heat than the stainless steel.
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