Answer: Option A. -> True
:
A
Laboratory thermometersare used to measure temperatureswith a high degree of precision.A laboratory thermometer has only the Celsius scale ranging from $-{10}^{\circ }C$ to ${110}^{\circ }C$.The boiling point of water lies within the range of a laboratory thermometer.

:
Each point: 1 Mark
Boiling:
1) It takes place througout the mass of the liquid.
2) It is a fast process.
3) It takes place at a fixed temperature for a particular liquid.
Evaporation:
1) It takes place only at the surface of liquids.
2) It is a slow process.
3) It takes place at all temperatures.

:
(a) Woolen clothes: 2 Marks
(b) Reason: 1 Mark
(c)Reason: 2 Marks
(a) We mustchoose two thin blankets instead of one thick blanket because woolen fibres trap air inside them, this air prevents the flow of heat from our body to the cold environment. When wehave two thin blankets, there is a layer of air trapped between the blankets. It prevents the heat flow.
(b)Stainless steel pans are usually provided with copper bottoms because copper is a better conductor of heat than stainless steel.
(c)The jerk to the thermometer will allow the mercury in or above the kink to flow into the bulb so that the mercury level is below normal temperature.

:
(a) Reason: 2 Marks
(b) Definition: 1 Mark
(a) During daytime, the land gets heated faster than the water. The air over the land becomes hotand rises up. The cooler air from the sea rushes in towards
the land to take its place. The warm air from the land moves towards the sea to complete the cycle. The air from the sea is called the sea breeze. To receive the cooler sea breeze, the windows of the houses in coastal areas are made to face the sea.
(b) The wind that flows from land to sea after sunset is called the land breeze.

:
Conductor: 1 Mark
Insulator: 1 Mark
Conductors are those materials which allow heat to flow through them easily, the phenomenon is called conduction.
Conduction usually takesplace in metals. Example copper, aluminum, etc.
Insulators are those materials which do not allow transfer of heat. For example wool, wood.

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Explanation: 2 Marks
Mode: 1 Mark
When we light a candle and keep one hand on the flame and the other on the side, the hand which is above the flame feels hotter.
Theair around the candle gets heated up and rises, cool air from the sides come and take its place.
Here, heat is getting transferred by convection.

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Each part: 1 Mark
Three scales of temperature are Celsius scale, Kelvin scale, and Fahrenheit scale.
The Celcius scale is followed in India.

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Each reason: 1 Mark
1) It has a low freezing point and a high boiling point. Hence it can be used for a wide range of temperature.
2) It has a shiny appearance due to which it can be easily seen through the glass of the thermometer tube.
3) It does not stick to the glass tube.

:
Use of kink: 2 Marks
Steps: 3 Marks
The kink in a clinical thermometer prevents the mercury level from falling. In the absence of kink, the mercury level would fall when wetake the thermometer out of the mouth.
The various steps to measurethe body temperature with a clinical thermometer are:

• Wash the thermometer, preferably with an antiseptic solution.


• Hold it firmly and give it a few jerks. The jerks will bring the level of mercury down. Ensure that it falls below 35°C.


• Now place the bulb of the thermometer under the tongue.


• After one minute, take the thermometer out and note the reading. This is the body temperature.

:
(a) Explanation: 2Marks
(b) Explanation: 1 Mark
(a) When sun-rays fall on objects, the objects get heated by different amounts. Some of them are hotter since they absorb more heat than the others. It has been found that dark coloured objects are better absorbers and transmitters of heat.
In places where the weather is hot, it is advised that the outer walls of houses be painted white because light colour reflects most of the heat that falls on it.Therefore, the temperature inside the house does not increase very much.
(b) Light colours reflect most of the heat coming from the sun and dark colours absorb most of the heat coming from the sun, that is why wearing light coloured clothes is much more comfortable than wearing dark coloured clothes in summers.