Q. I Select the correct options:
1. 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 convection
c. becomes cold by the process of radiation
d. does not become cold
ans: does not become cold
2. Stainless steel pans are usually provided with copper bottoms. The main
reason for this could be that:
a. copper bottom makes the pan more durable
b. such pans appear colourful
c. copper is better conductor of heat than the stainless steel
d. copper is easier to clean than the stainless steel
ans: copper is better conductor of heat than the stainless steel
Q. II Answer the following questions:
1. Why mercury preferred in thermometers?
ans: Mercury used due to following reasons:
• it expand uniformly
• it does not stick to wall
• it is shiny and easy to see
• it remain liquid at room temperature
2. What are the different modes of transfer of heat?
ans: Heat flows from higher to lower temperature till both bodies attend same
temperature. There are three mode of transfer of heat.
They are:
• Conduction: The mode of transfer of heat from molecules to molecules
without movement of particles.. Conduction takes place in solid as its
molecules ate closely packed. Solids, metals and alloy are good 17
CBSE Std. VII Term I Science Heat and its Transfer
conductor. Non metals, plastic glass are bad conductor of heat.
• Convection: The mode of transfer of heat from molecules to molecules
with movement of particles. In liquids and gasses heat transferred by
convection as molecules are far apart from each other.
• Radiation: The mode of transfer of heat that does not require any material
medium. Heat of sun reaches the earth by radiation.
3. What is a thermometer? What is a kink? What are different types of
thermometer?
ans: • Thermometer is an instrument that is used to measure temperature.
• It consists of long narrow glass tube having fine bore. There is a glass bulb
filled with liquid mostly mercury at the one end and sealed at other end.
There is small bend just above bulb called Kink. It does not allow the
mercury to fall as soon as taken out from our mouth.
• The different types of thermometer includes: laboratory thermometer,
clinical thermometer, mercury thermometer and alcohol thermometer.
Q. III Research aptitude and life skill:
1. Solar heat is used to cook food in two types of solar cooker- one in shiny
surface is used to collect heat: in the other a black box is used to collect
heat. Find out more about these two types of solar cookers and the reasons
for the difference.
2. In places of hot climate it is advised that outer walls of houses be painted
white. Explain.
ans: It is because the white colour reflects most of the heat that falls on it. Hence,
the outer walls of the houses in the places of hot climate are advised to paint
with white colour, so that most of the heat falling on these walls would be
reflected back. This will help in keeping the houses cool.18
CBSE Std. VII Term I Science Heat and its Transfer
Q. IV Solve the following crossword puzzle with the help of the hints provided
below:
1
2
5
3
4
ans: Across
2. Liquids and gases are
heated by this process
4. It does not allow heat to
pass
5. Heat is measured in this unit
Down
1. It is effect of heat
3.It is a form of energy
t
c o n v e c t i o n
m
p
j o u l e
r
a
h t
e u
i n s u l a t o r
t e
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
1. 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 convection
c. becomes cold by the process of radiation
d. does not become cold
ans: does not become cold
2. Stainless steel pans are usually provided with copper bottoms. The main
reason for this could be that:
a. copper bottom makes the pan more durable
b. such pans appear colourful
c. copper is better conductor of heat than the stainless steel
d. copper is easier to clean than the stainless steel
ans: copper is better conductor of heat than the stainless steel
Q. II Answer the following questions:
1. Why mercury preferred in thermometers?
ans: Mercury used due to following reasons:
• it expand uniformly
• it does not stick to wall
• it is shiny and easy to see
• it remain liquid at room temperature
2. What are the different modes of transfer of heat?
ans: Heat flows from higher to lower temperature till both bodies attend same
temperature. There are three mode of transfer of heat.
They are:
• Conduction: The mode of transfer of heat from molecules to molecules
without movement of particles.. Conduction takes place in solid as its
molecules ate closely packed. Solids, metals and alloy are good 17
CBSE Std. VII Term I Science Heat and its Transfer
conductor. Non metals, plastic glass are bad conductor of heat.
• Convection: The mode of transfer of heat from molecules to molecules
with movement of particles. In liquids and gasses heat transferred by
convection as molecules are far apart from each other.
• Radiation: The mode of transfer of heat that does not require any material
medium. Heat of sun reaches the earth by radiation.
3. What is a thermometer? What is a kink? What are different types of
thermometer?
ans: • Thermometer is an instrument that is used to measure temperature.
• It consists of long narrow glass tube having fine bore. There is a glass bulb
filled with liquid mostly mercury at the one end and sealed at other end.
There is small bend just above bulb called Kink. It does not allow the
mercury to fall as soon as taken out from our mouth.
• The different types of thermometer includes: laboratory thermometer,
clinical thermometer, mercury thermometer and alcohol thermometer.
Q. III Research aptitude and life skill:
1. Solar heat is used to cook food in two types of solar cooker- one in shiny
surface is used to collect heat: in the other a black box is used to collect
heat. Find out more about these two types of solar cookers and the reasons
for the difference.
2. In places of hot climate it is advised that outer walls of houses be painted
white. Explain.
ans: It is because the white colour reflects most of the heat that falls on it. Hence,
the outer walls of the houses in the places of hot climate are advised to paint
with white colour, so that most of the heat falling on these walls would be
reflected back. This will help in keeping the houses cool.18
CBSE Std. VII Term I Science Heat and its Transfer
Q. IV Solve the following crossword puzzle with the help of the hints provided
below:
1
2
5
3
4
ans: Across
2. Liquids and gases are
heated by this process
4. It does not allow heat to
pass
5. Heat is measured in this unit
Down
1. It is effect of heat
3.It is a form of energy
t
c o n v e c t i o n
m
p
j o u l e
r
a
h t
e u
i n s u l a t o r
t e
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
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