Ncert- science – class 7- Chapter 3 – Heat 1 Welcome to your Ncert- science - class 7- Chapter 3 – Heat 1 1. A metal spoon is placed in one of two identical cups of hot coffee. Why does the cup with the spoon have a lower temperature after a few minutes ? Energy is removed from the coffee mostly' by convection through the spoon. Energy is removed from the coffee mostly by radiation through the spoon. None of these Energy is removed from the coffee mostly by conduction through the spoon. None 2. Mark correct option or options : Moon's temperature is measured by thermometer Insect temperature is measured by thermocouple thermometer Sun temperature is measured by radiation pyrometer Both Sun temperature is measured by radiation pyrometer and Insect temperature is measured by thermocouple thermometer None 3. Mercury is often used in clinical thermometers. Which one of the following properties of mercury is not a reason for this ? The coefficient of the thermal expansion is large It has high density. It is shiny It is a liquid at room temperature None 4. A beggar wrapped himself with a few layers of newspaper on a cold winter night. This helped him to keep himself warm because Friction between the layers of newspaper produces heat. Newspaper is a conductor of heat. Newspaper is at a higher temperature than the temperature of the surrounding. Air trapped between the layers of newspaper is a bad conductor of heat. None 5. Two thermometers are used to record the temperature of a room and the bulb of one is wrapped in a wet hanky. The temperature recorded by the wet-bulb thermometer will be greater than that recorded by the other None of the above The temperature recorded by dry-bulb thermometer will be greater than that recorded by the other The temperature recorded by both will be same None 6. Thermal insulation is used to absorb heat stop the flow of heat reduce the flow of heat reverse the heat flow direction None 7. In which of the following process convection does not take place primarily? Warming of glass of bulb due to filament Trade wind Sea and land breeze Boiling of water None 8. Why is sense of touch not reliable? None of these It doesn't work for all of us It might misguide us It doesn't tell us what is hot or cold None 9. The standard fixed point for temperature measurement is used these days is : that temperature at which pure ice and pure water coexist that temperature at which ice, water and water vapour coexist melting point of ice at S.T.P. none of the above None 10. Choose the correct alternative:In the process of convection, heat travels upwards sideways downwards in all direction None 11. The velocity of heat radiation in vacuum is Greater than that of light Equal to that of light Less than that of light Equal to that of sound None 12. Snow is more heat-insulating than ice, because Air is filled in porous of ice Ice is more bad conductor than snow Density of ice is more Air is filled in porous of snow None 13. Woollen clothes are used in winter season because woollen clothes Are good sources for producing heat Absorb heat from surroundings Are bad conductors of heat Provide heat to body continuously None 14. A thermos flask is polished well To make attractive To absorb all radiations from outside To reflect all radiations from outside For shining None 15. The layers of the atmosphere are heated through Conduction (b) and (c) both Convection Radiation None 16. Weather reports are made using __________ thermometer Clinical Laboratary None of these Maximum-minimum None 17. If the temperature of a hot body is increased by 50% then the increase in the quantity of emitted heat radiation will be 400% 300% 200% 125% None 18. Which of these we could identify as cold with our sense of touch? A glass of water Cup of hot coffee Ice Hot tea None 19. Two thermometers are constructed in such a way that one has a spherical bulb and the other has elongated cylindrical bulb. The bulbs are made of same material and thickness. Then : cylindrical bulb will respond more quickly to temperature changes. spherical bulb will respond more quickly to temperature changes both bulbs will respond same to temperature changes none of both bulbs respond to temperature changes None 20. Glass cracks when heated; while a metal does not because Glass has pores inside None of these Glass is a bad-conductor Glass is bright None Time's up Please Share This Share this content Opens in a new window Opens in a new window Opens in a new window Opens in a new window Opens in a new window Opens in a new window Opens in a new window Opens in a new window Opens in a new window Opens in a new window Leave a Reply Cancel replyCommentEnter your name or username to commentEnter your email address to commentEnter your website URL (optional) Save my name, email, and website in this browser for the next time I comment.
