CBSE Questions for Class 7 Physics Heat Quiz 6 - MCQExams.com

In conductors, electrons can flow because their
    • ions are free
    • protons are free
    • electrons are free and mobile
    • negative ions are free
    Which of the following materials is an electrical conductor?
    • Silver
    • Silver-coloured plastic
    • Cork
    • Rubber
    Why are insulators important in an electrical circuit?
    • They make the circuit safe to touch.
    • Electricity will only flow through insulators.
    • Light bulbs and buzzers are only made of insulating materials.
    • All of the .above
    What is not an example of an insulator in the kitchen?
    • An oven mitt
    • A wooden spoon
    • Pots and pans
    • A plastic measuring cup
    When electrons in a material are free to move, the material is:
    • an insulator
    • a conductor
    • a semiconductor
    • none of these
    Which of these could be used to complete an electrical circuit?
    • A piece of gravel.
    • A rubber.
    • A crayon
    • Scissors made of iron
     Pure Water is an insulator.
    • True
    • False
    The outermost electrons are __________ and are called conduction electrons :
    • not free to move in the atom
    • bound to the protons
    • static
    • able to go to nearby atoms
    Which of the following would normally be the best conductor?
    • Copper
    • Glass
    • Steel
    • Silver
    Which material is a best conductor?
    • silver
    • porcelain
    • rubber
    • gold
    State whether given statement is True or False
    In a superconductor, electricity will flow for a long time and then stop.
    • True
    • False
    A clinical thermometer can not be used to measure
    • Room temperature
    • Human body temperature
    • Temperature of a boiling water
    • Temperature of a lake water
    .................. surface absorbs more heat than any other surface under identical conditions.
    • White & Shiny
    • White & Rough 
    • Black & Rough
    • Yellow & Shiny
    Why do we wear cotton clothes in Summer ?
    • Cotton is a bad conductor of heat and doesn't allow passage of warmer air near body.
    • Cotton is a good conductor of heat and allows body heat to escape in the atmosphere.
    • Cotton absorbs sweat from the body, exposing it to atmosphere for easy evaporation
    • None of the above
    Which of the following is the wrong pair of clothes worn during a particular season?
    • Cotton clothes during summer
    • Woolen clothes during winter
    • Dark colored clothes during summer
    • Polyester raincoats during Rainy season
    Which of the following fabrics is preferred for winter garments ?
    • Nylon
    • Cotton
    • Wool
    • Silk
    A laboratory thermometer can not be used to measure
    • Temperature of ice
    • Temperature of pond water
    • Temperature of human body
    • Temperature of boiling water
    The normal temperature of human body is ____________.
    • $$27^oC$$
    • $$37^oC$$
    • $$47^oC$$
    • $$57^oC$$
    How does air trapped by the woolen fabric help ?
    • Air is a good conductor of heat and allows warm air to come near body
    • Air is a bad conductor of heat and allows body heat to escape into atmosphere
    • Air is a bad conductor of heat and doesn't allow body heat to escape into atmosphere
    • Air is a good conductor of heat and doesn't allow cool air to come near body.
    Heat will flow from
    • Hot body to cold body
    • Cold body to hot body
    • two bodies at the same temperature
    • None of these
    Which of the following is a reason for using woolen clothes in Winter ?
    • Wool is an insulator of heat.
    • It traps a layer of air in its fabric.
    • Air being an insulator doesn't allow body heat to escape into the atmosphere.
    • All the above
    Cooking utensils are made up of 
    • Good conductors of heat
    • bad conductors of heat
    • neither good conduction not bad conductors of heat
    • None of these
    Which of the following is not a valid reason for using cotton clothes in Summer ?
    • Cotton clothes attract cool air.
    • Cotton clothes absorb sweat from the body.
    • Cotton exposes the sweat to atmosphere for evaporation
    • Cotton is light in weight.
    When a metal conductor connected to left gap of a meter bridge is heated, the balancing point.
    • Shifts towards right
    • Shifts towards left
    • Remains unchanged
    • Remains at zero
    A thermostat is?
    • A device used to maintain a constant temperature of a water bath or an oven
    • A modern type of thermoflask which work on the principle of equipartition of heat energy
    • An instrument by which the accuracy of thermometers is determined
    • A device which varies the temperature of a both
    What is the name of the process of heat transfer using electromagnetic waves?
    • Conduction
    • Convection
    • Evaporation
    • Radiation
    A cotton sheet is ironed with hot electricity. How is energy transferred through the metal base of the iron to the sheet?
    • by conduction only
    • by convection only
    • by radiation only
    • by convection and radiation only
    Sunlight contains ultraviolet radiations which makes it feel hot.
    • True
    • False
    Assertion (A): When hot water is poured in a thick glass tumbler then the tumbler breaks.
    Reason (R): Glass is a bad conductor of heat
    • A and R are correct and R is correct

      explanation for A
    • A and R are correct and R is not correct

      explanation for A
    • A is true and R is false
    • A is wrong and R is true.
    By which of the following methods could a cup of hot tea lose heat when placed on metallic table in a class room
    a) conduction
    b) convection
    c) radiation
    d) evaporation of liquid.
    • a, b
    • b,c
    • a,b,c
    • a,b,c,d
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