Science Revision test questions (Heat) class 7

HEAT

1. A beggar wrapped himself with a few layers of newspaper on a cold winter night. This helped him to keep himself warm because

    a.      newspaper is at a higher temperature than the temperature of the surrounding
   b.     newspaper is conductor of heat
   c.      friction between the layers of newspaper produces heat
   d.     air trapped between the layers of newspaper is a bad conductor of heat
Ans. d.     air trapped between the layers of newspaper is a bad conductor of heat

2. Paheli and Boojho measured their body temperature. Paheli found her's to be 98.6°F and Boojho recorded 37°C. Which of the following statement is true?
    a.      Both are suffering from fever
    b.     Paheli has a higher body temperature than Boojho
    c.      Both have normal body temperature
    d.     Paheli have lower body temperature than Boojho
Ans. c.     Both have normal body temperature

3. The heat in liquids and gases is transferred by the process of
    a.      Radiation
    b.     Convection
    c.      Conduction
    d.     Absorption
Ans. b.     Convection

4. During the night
    a.      Land cools more quickly than the sea
    b.     Sea cools quickly than the land
    c.      Land heats up
    d.     Sea water heats up
Ans. a.      Land cools more quickly than the sea

5. Conduction of heat does not take place in
    a.      Copper
    b.     Iron
    c.      Silver
    d.     Wood
Ans. d.     Wood

6. Dark-coloured clothes keep the body warm because they are
    a.      good absorbers of heat
    b.     bad absorbers of heat
    c.      neither good nor bad absorbers of heat
    d.      none of these
Ans. a.      good absorbers of heat

7. Water and air are _______ conductors of heat.
Ans. poor

2.    8.  _______ is the liquid used in thermometer.

    Ans. Mercury

        9._______ is the degree of hotness of the body.

    Ans. Temperature

4 10.The range of laboratory thermometer is ______________.    

    Ans. -10˚C to 110˚C

5.   11. The ______________ in clinical thermometer prevents the back flow of mercury into the bulb.

    Ans. Kink

    12.  In places of hot climate, it is advised that the outer walls of houses be painted white. Why?

\    Ans. In places of hot climate, it is advised that the outer walls of houses be painted white because white colour is a light colour and it reflects most of heat that falls over it. Hence, helps in reducing temperature of the house.

    13.   Identify two conditions that are necessary for conduction of heat.

    Ans. i) Difference between temperatures at the both ends of the object.

            ii) The objects at temperature differences must be in contact with the each other.

Popular posts from this blog

Friction (part-1)

FRICTION Q.1. What is force? Write few of its characteristics. Ans.1.  A push or a pull on an object is called a force.                      Force is a vector quantity (having magnitude  as well as direction).           S.I. unit of Force is N (Newton).           Force can Change the State of Motion.                   Force can Change the Shape of an Object. s          Q.2. What is friction ?      Ans.2.  The force which opposes the motion of an object on the surface of another object is called force of friction. Force of friction is a contact force. The force of friction always opposes the applied force (direction of motion).  
Read more

Sound (part -1) class 8

SOUND Q.1. What is sound? Ans. Sound is a form of energy, a sensation felt by our ears and makes us able to hear something. We hear many sounds around us like: sounds of talking, chirping of birds, ringing of bell, fluttering of clothes, machines etc. Q.2. What is the cause of sound? Ans. Vibration in an object produces sound. To and fro or back and forth motion of an object is called vibration. The energy required to make an object vibrate and produce sound is provided by some outside sources (like our hands, wind etc.). For example: We can feel vibrations by keeping our hand on our throat while speaking where vocal cords vibrate to produce sound. The sound of a ‘Dholak or tabla’ is produced by the vibrations of its stretched membrane on strucking. Q.3. Tabulate the Musical Instruments and their Vibrating Parts which vibrate to produce sound. Ans. S.No. Vibrating Part of Instrument Producing Sound Examples 1. Stretc...
Read more

Friction (part-2)

FRICTION Q.3.  Suppose your writing desk is tilted a little. A book kept on it starts sliding down. Show the direction of frictional force acting on it. Ans.3.                                 Q.4. What is the cause of friction? Ans.4.  Friction occurs due to the interlocking of irregularities between two surfaces in motion to each other. Every object has some sort of irregularities in its surface, so when two surfaces come in contact with each other and one object moves over the another, so their irregularities get interlocked and moving object starts losing its energy in breaking the interlocking and finally it comes to rest.                                             Q.5. What are the factors on which friction depends? Ans.5.  There are two factors affecti...
Read more