Class 7 Science Chapter 3 Question Answers - Heat

Q1: Define temperature.

Ans: The measure of hotness or coldness of an object is called temperature. It is usually measured in "degrees". 

Q2: Name the device used to measure temperature.

Ans: Thermometer

Thermometer

Q3: Name the two types of thermometers.

Ans:  Clinical thermometer and laboratory thermometer.

Q4: What do you mean by clinical thermometer?

Ans: The thermometer used to measure our body temperature is called a clinical thermometer.

Q5: The bulb in the thermometer contains _____________.

Ans:  Mercury

Q6: Thermometer should be washed before and after use with, preferably with an _________ solution.

Ans:  Antiseptic solution

Q7: Before use, the mercury level of the thermometer should be below __________.

Ans:  35°C

Q8: We should hold the thermometer by the bulb while holding it. True/False.

Ans:  False

Q9: What is the unit of temperature as adopted by India?

Ans:  Degree Celsius (°C)

Q10: What is the average body temperature of a healthy person?

Ans:  37°C

Q11: What is the range of laboratory thermometers?

Ans:  - 10°C to 110°C

Q12: Laboratory thermometer should be kept upright and not tilted. True/False.

Ans: True.

Q13: The bulb of the laboratory thermometer should not touch the surface of the ________________.

Ans:  Container.

Q14: What is the use of kink in a clinical thermometer?

Ans:  Kink prevents mercury levels from falling on their own.

Q15: Give an example to show the transfer of heat from one body to another.

Ans:  Any utensil kept on flame becomes hot because heat transfers from flame to the utensil.

Q16: Heat always flows from a hotter object to ________________.

Ans:  Colder object

Q17: In solid heat is transferred by the process of

a. Conduction

b. convection

c. Radiation

d. None of these

Ans: Conduction.  

Q18: Give examples of conductors.

Ans:  Aluminium, copper, iron etc.

Q19: Give examples of insulators.

Ans: Water, air, etc.

Q20: Insulators are ________ conductors of heat.

Ans: Poor

Q21: Conductors are _____________ conductors of heat.

Ans: Good

Q22: Name the process by which heat transfers in air.

Ans: Convection.

Q23: From the sun, the heat comes to us by the process called __________________.

Ans: Radiation.

Q24: Does the transfer of heat by radiation require any medium or not?

Ans: No

Q25: All hot bodies __________________ heat.

Ans: Radiates

Q26: If an iron rod at 30°C is dropped by chance into a bucket containing water at 30°C, will the heat flow or not?

Ans: No

Q27: A wooden spoon is dipped in a cup of ice cream, its other end

a. Becomes clod by the process of convention

b. Becomes hot by the process of conduction

c. Does not become cold

d. None of these.

Ans: Does not become cold  

Q28: Which of the two absorbs more radiation- a dark-coloured object or a light-coloured object?

Ans:  A dark-coloured object.

Q29: The temperature of boiling water cannot be measured by a ________________________.

Ans:  Clinical thermometer

Q30: Land breeze blows at the time of __________.

Ans: Night

Q31: Sea breeze blows at the time of _________.

Ans:  Day

Q32: Which type of clothing should be preferred for the month of June?

Ans: Light-coloured clothes

Q33: Which type of clothing should be preferred in January?

Ans: Dark coloured clothes.

Q34: A cold steel spoon is dipped into a cup of hot coffee. Will it transfer heat to its other end or not? If yes, then by which process?

Ans: Yes, by conduction.

Q35: One litre of water at 30°C is mixed with one litre of water at 48°C, which is the temperature of the mixture.

a. 48°C

b. 30°C

c. Between 30°C and 48°C

d. More than 48°C

Ans: Between 30°C and 48°C