:
(i) Heat : 2 Marks
(ii)How is it measured : 1 Mark
(iii) Explanation : 2 Marks
(i) Heat is a form of energy which flows from a hot body to a cold body.
(ii) A thermometer is used to measure the temperature of a substance.
(iii)In solids, generally, the heat is transferred by the process of conduction because particles of solids are closely packed and heat is transferred from the hotter end to the colder end of an object.

:
Clinical Thermometer: 1.5 Marks
Laboratory Thermometer: 1.5 Marks
The clinical thermometer is used to measure the temperature of human body. Hence, its use is limited for temperatures around 37 degrees Celcius. These thermometers thus have a range of 35${}^{\circ }$ C to 42${}^{\circ }$ C. It gives a more accurate measurement. It also has a kink, which holds the reading of mercury even when its taken away from contact.
Laboratory thermometers can be used to measure a variety of substances. These substances can be very hot or even very cold. For such reasons, it has a relatively broader area of measurement. These thermometers also do not have any kink, hence, the temperature is measured while the thermometer is still in contact.
Th range of laboratory thermometers is -10${}^{\circ }$ C to 110${}^{\circ }$ C.

:
Reasons:1 Mark each
Woollen clothes: 1 Mark
Dark coloured clothes absorb more heat so we feel comfortable in dark colouredclothes in winter.
We wear light colouredclothes in summer because they reflect most of the heat that falls on them.
Woollen clothes keep us warm during winters because they are poor conductors of heat. They trap our body heat, thus keeping us warm.

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.

Answer: Option C. -> Radiation
:
C
Out of all the modes of heat transfer, radiation is the fastest. This is because, it does not require any medium and it travels in the form of waves.

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 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 D. -> Reflection
:
D
There are three modes of heat transfer: conduction,convectionand radiation. Any energy exchange between bodies occurs through one of these modes or a combination of them. Conduction is the transfer of heat by physical contact.Convectionuses the movement of fluids to transfer heat.Heat radiationis the transfer of heatenergy through electromagnetic waves. Radiation doesn't require any medium.
Reflection means bouncing of light wave when it strikes an object. It is not a mode of heat transfer.

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 D. -> 35∘C−42∘C
:
D
A clinical thermometeris used to measurebody temperature. Itindicates temperatures from a minimum of ${35}^{\circ }C$ or ${94}^{\circ }F$ to a maximum of ${42}^{\circ }C$ or ${108}^{\circ }F$.