Q 1. State similarities and differences the laboratory thermometer and the clinical thermometer.
Answer : Similarities:
- Both have a bulb at one end.
*Both contain mercury in bulb.
*Both use Celsius scale on the glass tube.
*Differences:
- clinical thermometers have a kink to prevent the temperature but laboratory thermometers do not have a kink.
*A clinical thermometer reads temperature 35°C to 45°C while the range of laboratory thermometer is -10°C to 110°C
Q 2. Give two examples each of conductors and insulators of heat.
Answer:
Conductors: Aluminium,Iron
Insulators: Plastic, Wood
Q 3. Fill in the blanks:
(a) A cold steel spoon is dipped in a cup of hot milk. It transfers heat to its other end by the process of Conduction
(b) Temperature is measured in degrees Celsius
(c) No medium is required for transfer of heat by the process of Radiation
(d) Clothes of Black colours absorb heat better than clothes of light colours.
(e) The hotness of an object is determined by its Temperature
(f) Temperature of boiling water cannot be measured by a Clinicalthermometer.
Q 4. Match the following:
Q 5. Discuss why wearing more layers of clothing during winter ?.
Answer: More layers of clothing keep us warm in winters as they have a lot of space between them. These spaces get filled up with air. So, it does not allow the heat to escape out.
Q 6. Look at Fig. 4.2. Mark where the heat is being transferred by conduction, by convection and by radiation.
Answer:
Q 7. In places of hot climate, it is advised that the outer walls of houses be painted white. Explain.
Answer: White paint radiate more heat and absorb less. As a result, less outside heat would enter the house.
Q 8. One liter of water at 3000C is mixed with one liter of water at 5000C. The temperature of the mixture will be
a. 8000C
b. More than 5000C
c. 2000C
d. Between 3000C and 5000C
Answer: d.
Q 9. An iron ball at 4000C is dropped in a mug containing water at 4000C the heat will
a. Flow from iron ball to water.
b. Not flow from iron ball to water or from water to iron ball.
c. Flow from water to iron ball.
d. Increase the temperature of both.
Answer: b.
Q 10. A wooden spoon is dipped in a cup of ice cream. Its other end
a. becomes cold by the process of conduction.
b. becomes cold by the process of convection.
c. becomes cold by the process of radiation.
d. does not become cold.
Answer: d.
Q 11. Stainless steel pans are usually provided with copper bottoms. The reason for this could be that
- Copper bottom makes the pan more durable.
- Copper is better conductor of heat than the stainless steel.
- copper is a better conductor of heat than the stainless steel.
Answer: c. Copper is a better conductor of heat than stainless steel.
