Q1. State similarities and differences between the laboratory thermometer ad clinical thermometer.

Answer- Similarities between laboratory thermometer and clinical thermometer-

• Both are made of glass and consist of a long narrow uniform glass tube.
•   Both have a bulb at one end.
• Bulbs of both thermometers contain mercury
• Celsius scale present in both thermometer on the glass tube.

Difference between laboratory thermometer and clinical thermometer-

• Range of clinical thermometer is 35 degrees C to 45 degrees C while the range of laboratory thermometer is -10 to 110 degree C
• Clinical thermometer is used to measure the temperature oh human body while laboratory thermometer is used to measure the temperature in the laboratory.
• There is kink near the bulb in clinical thermometer, which prevent immediate backflow of mercury while no kink is present in laboratory thermometer.

Q2. Give two examples of each of conductor and insulators of heat.

Answer- Example of the conductor- copper, iron, aluminium, etc.

Example of the insulator- wood, plastic, etc.

Q3 . Fill in the blanks :

(a) The hotness of an object is determined by its ____________ .

Answer- Temperature

(b) The temperature of boiling water cannot be measured by a ___________ thermometer.

Answer- Clinical

(c) Temperature is measured in degree ____________ .

Answer- Celcius

(d) No medium is required for transfer of heat by the process of ___________ .

Answer- Radiation

(e) A cold steel spoon is dipped in a cup of hot milk. Heat is transferred to its other end by the process of ______________.

Answer- Conduction

(f) Cloths of ___________ colours absorb more heat better than clothes of light colours .

Answer- Dark

Q4. Match the following :

(i) The land breeze blows during                                           (a) summer

(ii) The sea breeze blows during                                               (b) winter

(iii) Dark coloured clothes are preferred during               (c) day

(iv) Light coloured clothes are preferred during            (d) night

    Answer-

(i) Land breeze blows during                                         (d) night

(ii) The sea breeze blows during                                    (c) day

(iii) Dark coloured clothes are preferred during          (b) winter

(iii) Light coloured clothes are preferred during           (a) summer

Q5. Discuss why wearing more layers of clothing during winter keeps us warmer than wearing just one thick piece of clothing.

Answer– More layers of clothing during winter keeps us warmer than wearing just one thick piece of clothing because we know the air is a bad conductor of heat it does not allow to escape of the heat from the body so when we wear more than one layer air gets trapped in-between layer.

Q6. Look at fig. 4.13. Mark where the heat is being transferred by conduction, by convection and by radiation.

         Attach fig from question ;

Q7. In place of the hot climate, it is advised that the outer walls of houses be painted white. Explain.

Answer–  It is advised to paint the outer wall of the house with white colour, in place of hot climate because white colour reflects heat and the house do not heat up too much. white is the poor absorber of heat. This helps in keeping the house cool.

Q8. One litre of water at 30 degrees C is mixed with one litre of water at 50 degrees C. The temperature if the mixture will be

(a)  80 degree C

(b) More than 50 degree C but less than 80 degree C

(c) 20 degree C

(d) Between 30 degree C and 50 degree C       

Answer- (d) between 30 degree C to 50 degree C

Q9. An iron ball at 40 degrees C is dropped in mug containing water at 40 degrees C. 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) not flow from iron ball to water or from water to iron ball

Q10. 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) does not become cold

Q11 . Stainless steel pans are usually provide with copper bottoms . The reason for this could be that

(a) Copper bottom makes the pan more durable

(b) Such pans appear colourful

(c) Copper is a better conductor of heat than the stainless steel

(d) Copper is easier to clean than the stainless steel.

Answer-  (c) Copper is a better conductor of heat than the stainless steel