Answer: Option A. ->
:
(a) Woolen clothes: 2 Marks
(b) Reason: 1 Mark
(c) Reason: 2 Marks
(a) We must choose 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 we have 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.

Answer: Option A. ->
:

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 we take the thermometer out of the mouth.
The various steps to measure the 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.

Answer: Option A. ->
:

Land Breeze with diagram: 2.5 Marks
Sea Breeze with diagram: 2.5 Marks
Sea Breeze: In coastal areas, during the day, the land gets heated faster than the water. The air over the land becomes hot and 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.

Land Breeze: At night, the water cools down more slowly than the land. So, the cool air from the land moves towards the sea.This is called the land breeze.

In both land breeze and sea breeze, heat transfer takes place by convection.

Answer: Option D. -> ${35}^{\circ }C-{42}^{\circ }C$
:
D

A clinical thermometer is used to measure body temperature. It indicates temperatures from a minimum of ${35}^{\circ }C$ or ${94}^{\circ }F$ to a maximum of ${42}^{\circ }C$ or ${108}^{\circ }F$.

Answer: Option A. -> True
:
A

Laboratory thermometers are used to measure temperatures with 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.

Answer: Option B. -> reading the wrong value
:
B
When a person does not read the thermometer by keeping the level of mercury along sight, there is a high possibility for him to observe a wrong value. To avoid this error, it is always advised to record thermometer measurements while keeping the mercury level straight at the eye level.

Answer: Option B. -> an insulator of heat
:
B
Wool contains a lot of air trapped between its fibres. This trapped air does not allow heat to pass from our body into the surrounding thereby keeping the person wearing it warm. Hence, it is an insulator of heat and we can wear woolen clothes in winter.

Answer: Option C. -> By placing the thermometer in the liquid such that it does not touch the base or the side of the container.
:
C

A kink is not present in laboratory thermometer. Therefore, the reading should be taken when the thermometer is immersed in the fluid. The thermometer should not touch the sides or the base of the container as the container may not have the same temperature as the fluid (especially if the container is not a very good conductor of heat). Thus, keeping the thermometer in touch with the container may give an inaccurate reading.

Answer: Option C. -> it does not have a kink
:
C

We cannot conveniently measure our body temperature using a laboratory thermometer mainly because it does not have a kink. The absence of a kink results in falling of the mercury/alcohol level as soon as thermometer is taken out to take the reading.

Answer: Option A. -> True
:
A
Metals expand on heating. Electrical wires being made of metals become warmer and expand in both length and diameter. That is why they sag. In winters, they are cooler and hence they shrink.