Answer:
1. Answer: (c) Temperature
Explanation: A reliable measure of the hotness of an object is its temperature.
2. Answer: (d) Thermometer
Explanation: Thermometer is used to measure temperature. The degree of hotness or coldness of a body is temperature.
3. Answer: (a) Mercury
Explanation: Mercury is filled in the bulb of a thermometer.
4. Answer: (a) 37°C
Explanation: The average normal body temperature is generally accepted as 98.6°F (37°C).
5. Answer: (b) from a hotter object to a colder object
Explanation: According to the second law of thermodynamics, heat will always from higher temperature to lower temperature, since the entropy never decreases over time.
6. Answer: (b) solids
Explanation: The method of transfer of heat in solids is called Conduction.
7. Answer: (a) radiation
Explanation: Heat from the Sun reaches is by the process of radiation. As we know radiation do not need any material medium for heat transfer.
8. Answer: (b) air trapped between the layers of newspaper is a bad conductor of heat.
Explanation: But the air molecules are not in a continuous contact and thus, the air trapped between the layers of newspaper does not conduct the heat. Thus, the layers of newspaper helped beggar to keep himself warm because the air trapped between the layers of newspaper is a bad conductor of heat.
9. Answer: (a) is a better conductor of heat than the wooden tile.
Explanation: Since, a marble tile is a good conductor of heat as compared to the wood, therefore a marble tile will allow heat to pass through itself easily, keeping it cool on a winter morning.
10. Answer: (b) Air
Explanation: The conductors are – Silver, copper, Aluminum, Nichrome, Graphite, Manganin, Mercury. The insulators are – Cotton, Air, Porcelain, Mica, Bakelite, Polyethylene, Sulfur.
11. Answer: (d) copper is a better conductor of heat than the stainless steel
Explanation: Stainless steel pans are usually provided with copper bottoms because copper is a better conductor of heat than stainless steel hence cooking of food becomes faster.
12. Answer: (c) don’t hold the thermometer by bulb
Explanation: It advised not to hold the thermometer by its bulb while reading it because the actual reading of human body temperature will get affected. This is for the reason that level of Mercury raises due to human body temperature.
13. Answer: (c) conductors
Explanation: The substances which conduct heat easily is called conductor. Heat is transferred from hotter end to colder end is known as conduction.
14. Answer: (b) convection
Explanation:: Land breezes and sea breezes arise because of differential heating between land and water surfaces. Moreover, the lower heat capacity of crustal materials often allows them to cool below the nearby water temperature. Air above the respective land and water surfaces is warmed or cooled by conduction with those surfaces
15. Answer: (a) Laboratory thermometer
Explanation: A laboratory thermometer, which is colloquially known as the lab thermometer, is used for measuring temperatures other than the human body temperature. It ranges from -10˚C to 110˚C. Laboratory thermometers are designed for lab purposes such as checking boiling point, freezing point, or temperature of other substances.
16. Answer: (b) Aluminium
Explanation: Some metals are better conductors of electricity than others. Silver, gold, copper, and aluminium are materials with free electrons and make good conductors. Silver is the best conductor of electricity, followed by copper, gold, and aluminium. Hence, Aluminium is a good conductor of electricity.
17. Answer: (d) land to sea
Explanation: A land breeze is a type of wind that blows from the land to the ocean. When there is a temperature difference between the land surface and the ocean, winds will move offshore. As the temperature of the land surfaces cool, the warm air rises and creates a small area of high pressure near the land surface.
18. Answer: (b) Cotton clothes
Explanation: Cotton is one the best fabrics for hot weather. Not only is it cheap and hugely available, but it is also great for the heat. Cotton is soft, lightweight, breathable, and soaks up sweat, allowing heat to escape the body and for you to stay cool.
19. Answer: (a) Black
Explanation: The more light the object absorbs, the more heat absorbed since light is energy. If you consider it a color, black absorbs the most heat. A black object absorbs all wavelengths of light and reflects none. Objects that are white, on the other hand, reflect all wavelengths of light and therefore absorb the least heat.
20. Answer: (b) summer
Explanation: Light colours are poor absorbers of heat. Light-coloured clothes are preferred in summer because Light colours are poor absorbers of heat. We wear light coloured clothes in summer because light colours reflect heat which helps our body to keep cool.
21. Answer: (c) Minimum and maximum thermometer
Explanation: Six's maximum and minimum thermometer is a registering thermometer that can record the maximum and minimum temperatures reached over a period of time, for example 24 hours. It is used to record the extremes of temperature at a location, for instance in meteorology and horticulture.
22. Answer: (d) Energy
Explanation: Heat as a form of energy because all of the many forms of energy, including heat, can be converted into work, amounts of energy are expressed in units of work, such as joules, foot-pounds, kilowatt-hours, or calories.
23. Answer: (c) 283 K
Explanation: We know,
K=C+273
K = 10°C + 273
= 283K
24. Answer: (c) Preventing heat loss
Explanation: The silver coated surface becomes shiny, so it reflects all the heat inside the wall, and it does not allow the heat to go out. And the layer of glass wall thermo flask is thin, so it prevents the loss of heat by conduction. Therefore, the thermo flask keeps cold liquid cold and hot liquid hot.
25. Answer: (d) condensation
Explanation: Condensation is the change of a substance from its gaseous form into its liquid state.
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